I have a 95 F150 4x4, how often should the fluid in the front and back differentials be changed and what is the best fluid to use? I didn't see a drain plug for the front am I missing something?

 

I think you have to loosen-up only of the bolts on front of diff. housing & let it drain slowly. If I am not mistaken your frt. diff. should be a Dana 44 IFS & has no drain plug or inspection cover.

Another idea, You could purchase one of those "suck" guns (looks like a grease gun) and suck the old fluid out through the lube fill hole.

I recently purchased one of the "suck" guns at local Harbor Freight Tool warehouse for about $6 (U.S.).

I am not for sure of the diff. lube change interval. I think it is usually noted in the Owners Manual.