dual range HydraMatics are different and require specialized tools than ANY newer generation automatic trannys. There are probably 5 shops in the US that can overhaul one. Last I heard, there was one in southern California.
I would recommend moving further questions on your truck onto a different forum.
https://oldgmctrucks.infopop.cc/eve?csra=Y&s=272004236
I would recommend moving further questions on your truck onto a different forum.
https://oldgmctrucks.infopop.cc/eve?csra=Y&s=272004236