sounds like some sort of 801D model.. menaing 172 ci diesel, and 58-62 model years. IE.. the model that was BEFORE the 4000 4 cyl that the seller is claiming it is.
unless it's a replacement trans from a 801 in a 4000 etc.
the middle digit you are missing will corespond to tranny and clutch style.
4 = 4spd, non live
5 = 5 spd, non live
6= 5spd, live