2.9 to 4.0 swap

[Harley17701]

i have an 88 ranger 4x4 with the 2.9 with the automatic w/overdrive and i know i somewhat seen this similiar question posted many times over different articles i seen .... now the question is . i have read that the 4.0 out of a ford explorer is easily doable to swap out ... and an identical transmission ... i been doing some research here but the answers of ... to do the swap would i need to change anything else out like ... transfer case or drive shafts or anything else out to match up with the 4.0 transmission and if not .... what year transmission would i be able to go with to match the 2.9 motor? ... and is it a big headache to install or no? ..... right now my situation sits like this ..... i have the headache 2.9 auto with overdrive .. and every time i pull a big hill the front pump seal leaks out. After doing some reading here i have read that alot of times that its just not worth going and having a new seal and such put in cause possible needing to go through it over and over and over again ..... so my idea here is to go with a transmission that if i need to put a little torque on that its not gonna blow as easy ... so i am looking for ideas here of transmissions that will bolt up ... and well as anyone little expense and headaches as possible ...