under § 881(a)(4) (conveyances, such as means of transporting drugs) or § 881(a)(7) (drug-related real estate) always constitutes punishment because the large and unpredictable variances in the value of conveyances and real estate can have no correlation to the costs incurred by the government and society as a result of the illegal drug trafficking for which the property is forfeited. United States v. Tilley, 18 F.3d 295, 299-300 (5th Cir.) (citing Austin v. United States, 509 U.S. 602, -, 113 S.Ct. 2801, 2803, 125 L.Ed.2d 488 (1993)), cert. denied, - U.S. -, 115 S.Ct. 574, 130 L.Ed.2d 490 (1994). On the other hand, a civil forfeiture of drug proceeds brought under § 881(a)(6) is never punishment. Tilley, 18 F.3d at 300; see United States v. Fields, 72 F.3d 1200, 1209 (5th Cir.1996) (<HOLDING>). In Tilley, we began our analysis by
holding that drug quantity is an element of an offense under 21 usc  841 recognizing that we held in tilley that the forfeiture of proceeds from illegal drug sales pursuant to 21 usc  881a6 does not constitute punishment holding that property held by another as nominal owner for benefit of a drug dealer subject to forfeiture under 21 usc  853 recognizing criminal forfeiture as an aspect of punishment recognizing that jury may infer from the evidence that defendants money came from drug sales