Ford has a hi-pinion dana 44 with a driveside drop to work with you 231 or 242 t-case plus it is about 30% or so stronger than a standard rotation dana 44. You have a hi-pinion dana 30 stock in there anyways so going with a hi-pinion dana 44 will give you a grood strength increase. The 76' Waggy dana 44 is also a passenger side diff so it wouldn't work with your current setup. 80' and up waggy dana 44 had a driverside drop.
Troy