ford 8.8 9 axle pinion

Can somebody help me? my b2500 posi differential has a weird movement. I've been told to change the differential. but mine is LSD and if I buy one at a junk yard most likely it wont be LSD. what other type of differential can I adapt to my truck? a mustang's? explorer?

i may be getting a ford 9" and d44 from a 78 f150 which i was wondering the best way to set up the drive shafts. i have a 8.8 in it now with a flange, i know the 9" has a yoke. and then theres the d44, ive read that the 78 d44 and my d35ttb both should have a 1310 series yoke.