Being a transmission guy, I have to say something about the GM conversions. Even though the right 200-4R will bolt up straight to the Olds (BPO) engine pattern, the 700-R4 is a much better conversion in so many ways. First of all, its torque handling is comparable to the 350, rather than the ultra light-duty 200 unit (which GM was actually sued for using), and there are probably more performance options for the 700 than almost any other unit! The sky is pretty much the limit on making it hold up to your engine. AND there is a valve kit available so you don't need ANY wiring going to the unit for lockup, which you really want if lower RPMs is what you're after! The 700 is shorter than the 200-4R, so requires less modifications to fit. Last year, I completed an overhaul on a 700 conversion in a $100k 55 Chevy (383 stroker) where a poorly installed "rebuilt" unit lasted only 40 miles. It is now happily doing donuts if it wants to! And one of my good customers just had me do a full 350-700 conversion on his 71 Chevelle that he keeps looking mostly stock but wanted lower RPMs on the freeway. He is very happy with it. Buy an Olds-Chevy case adapter if you want overdrive on your old BPO setup! Otherwise, get a Gear Vendors, but it'll likely cost you more and require electronics and more maintenance.
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