48s are a tad big for a dd

It isn't so much that any tire size is "too" big for a dd, rather it depends on the goals.
If the trail riding or rock crawling you want to do requires a 35" tire for reasonable performance, then that is a good dd tire size and build the rig to work with that.

Also it isn't the size so much (oh god where am I going) it is the type and brand that determines a good or bad dd tire.
(whew)

A swamper bias ply tire is almost always a crappy dd tire.
On the other hand a Parelli may not work so well on the trail.

A good street trail tire that runs quiet, lasts, looks good and is a proven trail performer anywhere in the US (mud, rocks, and gravel is the BFG MT. OR Goodyear MTR.
They both stink on soft beach sand. A wider less agressive tire is best for the beach.

Axles, d44 from a 88-91 grand wag that has the d side drop diff, the rear from the same can work provided it is a d44 not the m20. They came with both.
Watch out for the the funky vac disco front 44 that came in those years. Most were the good ones.

Both need some mods for bolt up, spring perch relocation and on the front a massaging of the spring pad on the diff side. yj is 31" frame center, the wag is 32. So both sides need to be moved in 1/2".

If you wish contact me through PM or email if you want me to build and ship complete axles to you.

SD