4.0L Engine Interchangeability

I picked up an '01 XJ with the 4.0L engine and AW4 auto trans. The engine had rod knock so I've pulled it and want to swap in a good, used engine from a junkyard. I'm steering clear of the '00-'01 XJ engines because of the 0331 head cracking issues, but wanted to know how broad I can make my search. I realize that if I use anything other than the 0331 head, I'm going to have to use a different exhaust manifold and I'm alright with that (or I might get one of the adapters to use the 0331 manifolds...no big deal).

Are 4.0L's from Grand Cherokees and Wranglers a direct drop in? I'm trying to get a range of years on specific models that I can search for. So far, I know '96-'99 XJ's should be fine, but don't know what else.