Can anyone tell me what the stock gear ratio was in the R180 rearend and the R200 rearend. Also, did the gear ratio change with the year of the Z even though they had the R180 or R200 chunk.

I suggest you visit Z-home and click 'transmission calqulator' or one of the other references to 'stock' ratios that varied from year to year and model. Auto's got this one, 2+2's got that one and turbo's got another one..... As a fairly large blanket statement, it is pretty safe to say 'stock' assumption for 80+% of all 1st gen Z's in the US in regards to diffy ration will be something very close to 3.5:1.

steve77

here is a site that will give you all the info. geocities.com/zgarage.2001/engine.html check it out. Gary

Much if not all of the info you are looking for is located in this thread, thanx to 2many!

http://www.classiczcars.com/forums/showthread.php?s=&threadid=1568&perpage=15&pagenumber=2