I just purchased a 98 LS 4 door Blazer and it has the p1780 code . I didn't know what it was and I still don't know much about it but I found another trans that I was told come out of a ZR2 but I'm not sure on year . My question is , is there a difference in the gear ratios ? I know mine has a 342 ratio because it has the original window sticker with it . If anyone could help me with this I would be grateful . Thanks

 

The gear ratio is in the differential(s), not the transmission. You just have to make sure its the right transmission, I beleive your truck would have a 4L60E - automatic transmission 4 speeds plus overdrive. The ZR2 should have the same transmission just have different gears and bigger tires.

 

Thanks for the info . I knew the gears are in the diff , I just didn't know for sure if the gear ratios was different between the two . I know mine has the 342 , I kinda wish it had a 373 so maybe ill just change it all around . Thanks again