You might look for a 3rd member from a '67-'72 3/4 ton, they have more rpm freindly ratios, 4.10 is common, and will go right into your existing rear end housing. The turbo 700 would be a good coice if you change the trans, it has a deeper 1rst gear than the th350/400, plus the overdrive. Just get the later version, the '85 and earlier have weak pumps.
