the present invention is utilized in a tufting machine of the type generally including a needle bar carrying one or more rows of longitudinally spaced needles and which is supported and reciprocally driven by a plurality of push rods . in the tufting zone , the needles carry yarns which are driven through a backing fabric by the reciprocation of the needles . while penetrating the backing fabric , a plurality of longitudinally spaced hooks cooperate with the needles to seize loops of yarns and thereby form the face of a resulting fabric . in some cases the hooks will cooperate with knives to cut the loops of yarn seized on the hooks and thereby form a cut pile face for the fabric . the present invention is directed to modular units for holding loopers or hooks and for holding needles to facilitate their cooperation during the tufting process . referring in detail to fig1 a modular block assembly 5 is illustrated having a single row of gauge elements 10 , in this case loopers , housed in the modular blocks 15 . the individual gauge elements 10 are fastened to the block 15 by securing pin 20 . as better illustrated in fig2 the securing pin 20 enters the modular block 15 at one of the opposing side surfaces 22 a , 22 b . the gauge bar 25 and guide bar 30 are used in concert to position the individual modular blocks 15 relative to one another . the guide bar 30 slides laterally through channel 35 substantially the entire length of the gauge bar 25 , and engages tab breaks 115 of the modular blocks 15 , as shown in fig3 to vertically align the individual blocks 15 . fig2 illustrates a portion of the modular block assembly 5 with the blocks 15 detached from the gauge bar 25 . the gauge bar 25 has a plurality of vertical recesses 40 . the recesses 40 are crossed by lateral channel 35 so that guide bar 30 fits between the gauge bar 25 and the rear surfaces 45 of the modular blocks 15 . guide bar 30 creates upper face 31 and lower face 32 which are normal to the side walls of recesses 40 . theses faces 31 , 32 serve as restraining surfaces . one modular block 15 in fig2 is disassembled and removed from the gauge bar 25 to reveal the spaced parallel slots 50 divided by vertical walls 51 located on the front surface 55 of the block for receiving the proximal ends 75 of the gauge element 10 . the proximal ends 75 of the gauge elements 10 contain apertures such as pin holes 70 . when the gauge elements 10 are positioned in the modular block 15 , the pinholes 70 align with apertures formed in side surfaces of the block such as pin opening 85 . securing pin 20 is then inserted through the pin opening 85 in one of the opposing side surfaces 22 a , 22 b , and the pin opening 85 for each gauge element 10 to fasten the gauge elements 10 to the block 15 . in modular blocks 15 containing only a single row of gauge elements 10 , a tongue portion 60 extends from the rear surface 45 of the modular block 15 . the tongue 60 forms the detent . the tongue 60 has an opening 90 , as shown in fig3 preferably in the form of a threaded hole which aligns with another hole 100 , located in a gauge bar recess 40 , when the modular block 15 is positioned on the gauge bar 25 . once a modular block 15 is positioned a securing screw 65 can be inserted through the opening 90 and tightened into the hole 100 on the gauge bar . a modular block 15 , once fixed in place by the securing screw 65 , is prevented from lateral and vertical movement . the screw 65 and vertical recesses 40 resist against horizontal movement while the screw and faces 31 , 32 of the guide bar 25 resist against vertical movement . the fixed position of the blocks 15 insures that the gauge elements 10 remain properly aligned during the tufting process . fig3 shows the rear surface 45 of a modular block 15 having a single row of gauge elements 10 . on the rear surface 45 is an elongated tab 110 that extends vertically from the top 165 of the block to the bottom of the tongue portion 60 of the block . the tab 110 has a horizontal break 115 which as previously described engages with guide bar 30 to vertically position block 15 on the gauge bar 25 . the walls of break 115 are preferably substantially planar and parallel so that a part of the rectangular cross section of guide bar 30 closely fits within the break . the lower segment of the tab 120 contains the opening 90 where the securing screw 65 enters and attaches to a receiving hole 100 in the gauge bar . fig4 illustrates a modular block assembly 5 having three double gauge element modular blocks 130 mounted on the gauge bar 26 . each modular block 130 contains two gauge element rows 125 . modular blocks 130 have two apertures such as pin openings 85 a , 85 b that are spaced apart on the side surfaces 22 a , 22 b of the block 130 . unlike single gauge element blocks 15 , a portion of the double gauge modular blocks 130 rests on top of the gauge bar 26 to vertically position blocks 130 . this is accomplished by pushing the tongue 60 forward to the center of the bottom of the block 135 . fig5 shows an exploded view of modular block 130 containing two rows 125 of gauge elements 11 , 12 . the gauge bar 26 in fig5 has a plurality of vertical recesses 40 . vertical recesses 40 receive tongues 60 to horizontally position blocks 130 along the gauge bar 25 . vertical positioning is accomplished by resting part of the bottom surface of gauge blocks 130 on the top surface of gauge bar 25 . the modular block 130 in fig5 is disassembled and removed from the gauge bar 26 to reveal the spaced parallel slots 50 a , 50 b located on the front 55 and rear surface 45 of the block 130 for receiving the proximal ends 75 , 78 of the gauge elements 11 , 12 . the proximal ends 77 , 78 of the gauge elements 11 , 12 contain openings such as pin holes 71 , 72 which when positioned in slots 50 a , 50 b of modular block 130 align with pin openings 85 a or 85 b , respectively . the securing pins 20 a , 20 b are inserted through the pin openings 85 a or 85 b on one of the opposing side surfaces 22 a , 22 b and through pin holes 71 , 72 for each gauge element 11 , 12 to fasten the gauge elements 11 , 12 to the modular block 130 . in the illustrated modular blocks 130 containing two rows 125 of gauge elements 11 , 12 the tongue portion 60 of the modular block 130 extends from the center of the bottom surface 135 . the tongue 60 defines an opening 90 ( not shown ) which aligns with receiving holes 100 , located in the vertical recesses 40 , when the modular block 130 is positioned on the gauge bar 26 . once the modular block 130 is positioned a securing screw 65 can be inserted through opening 90 and tightened into a threaded receiving hole 100 . the modular block 130 , once fixed in place by the securing screw 65 , is prevented from lateral and vertical movement . the fixed position of the block 130 insures that the gauge elements 10 remain properly aligned during the tufting process . referring now to fig6 another aspect of the present invention depicts a modular block assembly 5 having a single row of gauge elements , in this case needles 13 , housed in a clamping modular block 140 . fig6 shows four clamping modular blocks 140 attached to the gauge bar 27 . the clamping modular blocks 140 are positioned such that the lower portion 150 of the block 140 extends beneath the gauge bar 27 . this exposed lower portion 150 contains the individual clamping elements , such as screw - pins 145 , shown in fig7 that hold the gauge elements 13 in place in the block 140 . the gauge bar 127 has a horizontal shelf portion 27 a and a vertical portion 27 b which join to form an interior right angle . fig7 illustrates a portion of a modular block assembly 5 with screw - pin modular blocks 140 detached from the gauge bar 25 and one block 140 disassembled . the gauge bar 27 has a plurality of vertical recesses 40 imposed on the front of the gauge bar 27 . as illustrated , the recesses 40 do not extend the entire height of the wall portion 27 b of the gauge bar 27 . each recess contains a preferably threaded hole 100 which receives a securing screw 65 to attach the block 140 to the gauge bar 27 . the rear surface of the modular block 45 contains a rectangular tab 160 having an opening 90 , shown in fig8 which aligns with the hole 100 , located in the gauge bar vertical recesses 40 . once the modular block 140 is positioned in the right angle between the shelf portion 27 a and wall portion 27 b , with tab 160 received in a vertical recess 40 , the securing screw 65 can be inserted through the corresponding hole 100 in the wall portion 27 b into the opening 90 in the rectangular tab 160 and tightened to hold the modular block 140 in place . once fixed in place by securing screw 65 , the modular block 140 is prevented from lateral movement by the action of the tab 160 fitting with the walls of the vertical recess 40 , the screw 65 , and adjacent blocks 140 . horizontal movement is restored by action of the screw 65 at the bottom of shelf portion 27 a of the gauge bar 27 . the fixed position of the block 140 insures that the gauge elements 10 remain properly aligned during the tufting process . fig7 also depicts a disassembled clamping modular block 140 thereby revealing the spaced parallel gauge element openings 155 which extend from the top surface 165 to the bottom surface 135 of the block 140 . openings 155 need not extend completely to the top surface 165 for satisfactory operation , however , it is convenient for manufacture . the individual needles 13 are fastened to the block 140 by dedicated clamps such as screw - pins 145 that fix individual gauge elements 10 within the block 140 . screw pins 145 enter the block 140 at the rear surface 45 of the block 45 on its lower portion 150 . when the block is attached to the gauge bar 25 the screw - pins 145 remain accessible so that individual gauge elements 10 can be removed and replaced . fig8 illustrates the top 165 and rear surface 45 of the block 140 . gauge element openings 155 can be seen on the top surface 165 of the block 140 . the rectangular tab 160 for positioning the block 140 on the gauge bar 25 is located centrally on the rear surface 45 of the block 140 . the rectangular tab 160 defines the opening 90 which aligns with the holes 100 in vertical recesses 40 and with securing screw 65 fixes the block 140 to the gauge bar 27 . openings 170 for screw pins 145 are located horizontally along the lower portion 150 of block 140 . although a preferred embodiment of the present invention has been disclosed in detail herein , it will be understood that various substitutions and modifications may be made to the disclosed embodiment described herein without departing from the scope and spirit of the present invention as recited in the appended claims .