slipyoke

I spent the day today swapping out my 8 1/4 for a 8 3/4 ...new 10 x 2.5 brakes new dr diff axels changed bushing on my springs and a few other things..when i got finished i looked at the d/s hanging out the rear of the 833 and thot that shaft is going to fit..now this shaft came out of a 318 904 8 1/4 74 duster and darn if it didnt slide in the pinion yoke i just put in and bolt up..only problem,is it only has about 3/4 of an inch slip room before it bottoms out..now iv been using it with a 4 speed 833 and a 8 1/4 rear now its using same 833 but a 8 3/4 now...are they that close..while under there i got a measurement of 49 7/8 from face of yoke to center of u joint..