/6 904 info help

So i finally got my 78 b100 home. Was gonna see about getting more info on the tranny. Thought it was a stick cause there was still a clutch pedal I. The van lol. At least I'm pretty sure it's a 904. Anyway I tried cleaning a little bit to find numbers but havent gotten to lucky lol. I plan to sell this and don't want to give false info or charge to much a d do t want to short myself to much either.
I've scraped some of this oil off lol found some numbers here and there but don't know which to look at but I don't think I've found the right ones either.
Sucks that I'm gonna be chopping this up. Other than a dusty surface rust in one tiny area I haven't found any actual rust anywhere

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