“ oem ” means a motor vehicle part that is manufactured to the specifications of the original equipment manufacturer . normally this means the part is made by or for the original equipment manufacturer . fig1 is a perspective exploded view of an exemplary conventional truck engine 100 with a standard ford ® oem dual alternator installation 102 including a first standard alternator 104 and an optional second alternator 106 . all parts in fig1 are oem . standard alternator 104 is mounted on a standard alternator - power steering bracket 108 and affixed to bracket 108 by three alternator bolts 112 . optional alternator 106 is mounted on an optional alternator bracket 110 and affixed to bracket 110 by three alternator bolts 112 . bracket 110 is , in turn , affixed to the front 114 of block 116 of engine 100 . a flexible belt or chain ( not shown ) is subsequently placed around a crankshaft pulley 118 , a pulley 120 on alternator 104 and a pulley 122 on alternator 106 to power alternators 104 and 106 . the belt or chain may also power other components such as an air conditioning compressor 124 and a power steering pump 126 . fig2 is a perspective exploded view of engine 100 with alternator 104 removed from bracket 108 in preparation for installation of an alternate exemplary mounting adapter and accessory ( described below ). the simplicity of this removal is apparent . as in fig1 all parts are still oem . fig3 is a perspective exploded view of engine 100 with exemplary optional alternator bracket 110 , but with a belt - driven hydraulic pump 300 mounted on an exemplary accessory adapter 302 by two accessory mounting bolts 304 . adapter 302 is , in turn , mounted on bracket 108 by three adapter mounting bolts 306 , which are configured to thread into three bolt holes 308 , 310 , and 312 already existing in oem bracket 108 . it will be understood that pump 300 and adapter 302 could instead be mounted on optional bracket 110 in place of optional alternator 106 . if adapter 302 is mounted on bracket 110 , standard alternator 104 is be mounted on bracket 108 . it is preferred to place pump 300 and adapter 302 on bracket 108 to allow any hydraulic hoses and fittings to be more easily installed . the exemplary installation of fig3 shows the simplicity of the mounting in contrast with the prior art c . w . mill installation . the only non - oem parts in fig3 are bracket 302 , bolts 304 and 306 , and pump 300 . pump 300 has a pulley 314 that would be driven by a standard serpentine belt ( not shown ) in similar fashion to the manner in which pulley 120 was driven . pulley 314 is aligned with pulleys 118 and 122 , since pulley 314 occupies the space previously occupied by pulley 120 . the use of bracket 302 permits a simple method of installing belt - driven accessory 300 on truck engine 100 . a typical situation where that might be desirable is in a truck having a hydraulic lift ( not shown ) needing hydraulic fluid pump 300 . conventional dual alternator mounting 102 is modified by substituting for one of the two alternators 104 , 106 adapter 302 adapted to attach to both accessory 300 and one of the dual alternator mounts 106 , 108 . adapter 302 makes the addition of a hydraulic pump an easy assembly using all oem parts except adapter 302 , adapter bolts 306 and accessory 300 . one exemplary accessory installation method is to order a truck with a dual alternator installation 102 . the standard alternator 104 is then be removed in conventional manner by loosening or removing the serpentine belt ( not shown ) from alternator 104 , unbolting bolts 112 , and lifting alternator 104 out of bracket 108 . accessory 300 is bolted to adapter 302 using two accessory mounting bolts 304 and adapter 302 and accessory 300 , as a unit , are mounted in bracket 108 by three adapter mounting bolts 306 . adapter 302 is configured to align pulley 314 in the same plane as was pulley 120 . two 3 . 5 ″ diameter back idler pulleys ( not shown ) are replaced by two 3 ″ diameter oem back idler pulleys to help compensate for the increased size of pulley 314 relative to pulley 120 . the drive belt is then tightened back in position except that now it passes around pulley 314 rather than pulley 120 . the hydraulic hoses ( not shown ) are installed to connect pump 300 to whatever device is to be powered . using adapter 302 , the total installation time for pump 300 on engine 100 is reduced to about 1 hour . adapter 302 is one of many possible configurations specially shaped to match brackets 108 and 110 . in this exemplary embodiment adapter 302 is made by forming a rectangular ¼ ″ or thicker steel plate into a channeled or recessed configuration with a flat base 322 , two inclined transitions 314 and 316 , and two flat wing portions 318 and 320 . base 322 is a flat rectangular steel plate . transitions 314 and 316 are two inclined steel plates integral with and extending upwardly and outwardly from opposite edges of base 312 . wing plates 318 and 320 are two flat steel plates integral with and extending outwardly from opposite outer edges , respectively of transitions 314 and 316 . wing plate 318 has two holes configured to match holes 308 and 310 of bracket 108 . wing plate 320 has one hole configured to match hole 312 of bracket 108 . base 322 has two holes 330 and 332 configured to match two similar holes ( not shown ) in the bottom of accessory 300 and to receive bolts 306 . adapter 302 is thus configured to allow accessory 300 to be attached to bracket 108 in substitution of alternator 104 . transitions 314 and 316 cause base 322 to be depressed relative to wing plates 318 and 320 so that base 322 can fit into a depression in bracket 108 . this allows accessory 300 and adapter 302 to be mounted onto bracket 108 without accessory 300 interfering with closing of the hood ( not shown ) of the truck ( not shown ) in which engine 100 is located . adapter 302 could alternatively be mounted in optional bracket 110 in place of alternator 106 , but , where accessory 300 is a hydraulic pump , that is less desirable since it is much harder to route hydraulic lines under engine 100 than above engine 100 . adapter 302 can be modified if needed to fit a different alternator or accessory - mounting bracket . for example , base 322 , transitions 314 and 316 , and wing plates 318 and 320 can be curved , shortened , lengthened , thickened or thinned if that fits the shape of the mounting bracket 108 better . fig4 is a perspective view showing one such alternative exemplary adapter 400 . adapter 400 has a vertically curved base 401 and two vertically curved transitions 402 and 403 connecting base 401 to horizontally curved wing plates 405 and 406 , and baseplate 401 has a horizontally curved rear portion 404 , all with the purpose of minimizing the amount of metal and eliminating sharp corners . exemplary adapter 302 is customized for a 1997 - 2000 7 . 3 liter ford ®, international ®, or navistar ® diesel engine using only oem components . if the accessory mounting bracket for any vehicle engine is different from those three , then the shape of adapter 302 would be modified to adapt . likewise , if the accessory fastener portions are studs rather than bolt holes , are different in number than two , are spaced or sized differently , or are recessed or extended , the base could be modified within the scope of the appended claims to adapt to such modifications . while the invention has been described in terms of various specific embodiments , those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims .