C4 ffford question

[goinbroke2]

I have a truck c4 (pan fill not case fill) and I want to order a converter, question is, are all pan filled c4’s 26 spline or did they vary between 24 and 26 depending on year?(like the case filled ones do)
I have a 3000 stall in it now, but that was put in, in 1994 or so and I don’t remember what I installed. (Thinking 26 but I’m not ready to rip it apart yet)

Thanks