I'm building a switch-pitch TH400 to go in front of a 203/205 doubler. I have three 400s-a '64.5-'67 Caddy, a '78-'79 w/203 tcase (unknown GM engine) and a '85 6.2 diesel w/205 tcase. What I want to know, is what are the best pieces of the three to use to get the strongest unit? The Caddy trans has 34 element sprags and 4 gear planetaries (Do they all?). Are there differences between the gas and diesel chevy cases, strengthwise? I've only disassembled the Caddy trans so far so I don't know what's in the other two yet. This is my first auto tranny adventure. I'd like to put in a 3:1 low planetary, but it's ~$700... any thoughts/advice?