[ratbox]

definately not an expert . but i disagree in the statement that zl-1's were the same engine as l-88 only with aluminum block. i'm not sure what else(probably more) .but i know that the cam's were differant . L-88 -#3925535 .540 intake/.560 exhaust-duration 326/334. ZL-1 -#3959180 .560 intake/.600 exhaust- duration 322/334.
.also found on HD parts list-pushrods # 3942415,3942416(intake/exhaust)with listing desription "Pushrod,intake,427-CID w/heavy duty aluminum block.7/16-in.diameter."so obviously they used a differant pushrod. and i'm sure there are other differances also. ie; possibly carb - maybe more.there's another interesting part listed on "HD" list-#3967811, despription "Crankshaft-1968(?)-'69 aluminum-block 427 CID.3-49/64-in. stroke,5140 steel forging w/cross-drilled mains.Nitride finnish on journals.2.1985-in.rod,2.748-in. main journal diameters.(Ident.7115). both of those parts have a desription that mention for "aluminum block", so they must be specific.and their are probably other parts and processes TO parts(treatments) that are differant. but it definately is a differant motor with differant specs. i have know idea about build sheet's and rpo's(possible two step rpo order to get one-manditory l-88?) for these cars as i have never seen one. but i would doubt it. maybe the build sheets with rpo l-88 also were put there so the builders would know to put on the rest of the applicable components (like special brakes and suspension) as they might have already been instructed as to what an l-88 car consisted of and how to build one. and the zl-1 rpo was less familiar. so a helpful guideline for assembly workers? i don't know, just a possible guess.that's all i could remember off the top and with a quick look in my library. note- remember not related to production cars, but they also made ZL-1's that were different from production car ZL-1's. that had some differant parts from normal ZL-1's for Can-am applications ie; even higher lift cam(.600/.600) and gear drive. probably even more differant parts(and massaging) here too.