Quote:
Originally Posted by 68c10owner
GM decided there was good cause for a change but please enlighten us as to why there isn't much difference.
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Off the top of my head, Up through '84 the input shaft was the same size as the 200-4R. The biggest improvement in the early models was a simplified forward sprag and improvements to the pump to make it more reliable.
1986 the low roller was strengthened from the previous TH350 piece it was using.
1987 Hydramatic redesigned the case to accept a forward accumulator system to cushion shock going into drive. Some one-piece seals replaced scarf cut seal previously used and the pump vane count was increased again.
There were other minor changes made through the years. Many of the changes retrofit to earlier models. Some items, do not retrofit backwards but I don't see them as a big deal.