So... The 4 bolt side cover is the same length as a 7 bolt? I have a line on a 4 bolt now but I have a 7 bolt straight 3 speed in the truck now. I take it the tail shaft spline for the 4 bolt is different than the 7 bolt. Also, what part of the linkage do you need to change? The listing says the 4 bolt I'm interested in came out of a 67 Belair. So I take it the 7 bolt comes out of a later model.
I found this on Ebay. If you read the description, it says to call this place for solenoids and governors.
https://www.ebay.com/itm/SAGINAW-3-S...frcectupt=true
Here is the link to the thread on the 4 bolt
http://67-72chevytrucks.com/vboard/s...45#post8386745