I have to replace the flex plate in my 88 dodge dakota 3.9 truck but I need to know what trans I have. I know it is a 3speed automatic but I know there are a couple of options.

32RH a999
36rh a727

Any help would be appreciated. I also know this is not the original engine or trans in this truck.

Its a 32RH, Because your truck is light duty not heavy, Thats what 36RH is.