OK - I made a trip to my storage trailer today to look at my core lockup transmission. Turns out (according to Mr. Hand's book) it is a 998 out of a 1980 Chrysler. Just looking at it, it is Very similar in case/tailshaft housing dimension. This is as compared to a 1965 cableshift gearbox. Should fit right in the same space.
That being said, does anyone know if that particular breed of 904 have any particular problems? it's a 4130956. It should have a lot of the upgraded parts and a 4 disc front clutch retainer as well as the wide ratio gearset. (some of the early 998's even had 5 disc clutches - but that would be too much to ask for!)
While I was messing around, I pulled the cooler line fittings off and took a look down the outlet hole. It is quite close to .250" (sits back in there a ways and I didn't have my inside mic handy) So, now I am wondering, just Why would I need to have cooler lines any larger than that??? The inside diameter of the fittings (-4 to 1/8" pipe) is even smaller - around .228 at best. I pulled a stainless AN -4 to 1/4 pipe thread adapter out of my parts bin and even it was less than .250! So - what we have here is not one, but two flow restrictor orifices. Not gonna get much, if any, better flow with larger lines. (same volume, less velocity) That being said, I will still put -6 (3/8") lines to my cooler, just because it makes me feel better. And the guy you run over will say "Wow, look at those fancy cooler lines!"