I bought an 85 trans am from my friends brother for 700 bucks that has a tpi 350 that the owner before him had it put in. I am going to swap this motor into my formula but I was looking at it last night and i compared the balancers and the one on my tbi is seriously almost twice the size of the tpi balancer. Do i have a 350 tbi and not know it and the tpi is actually a 305? Or is there a reason for a tpi to have a smaller balancer?

 

No, but damper size varied from year to year and application to application.

I had a '71 GMC with a 350 that had a dinky damper.