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Ok guys, let me start off by saying that I'm swapping from a 2.5L/AX4/NP207 to a 4.0L/AX15 (external slave)/NP231 or NP242 (not sure which yet). Past few nights, I've been working on tearing out the 2.5 in my '86. I have a '90 XJ with AW4 as my donor. However, lets forget about it being an '86 for a second because I have a few general questions about the 2.5 to 4.0 swap that I haven't quite been able to find in the vastness that is the interwebz... Here goes (they'll be more as issues arise): On the AX4/5 equipped MJs, the end of the exhaust downpipe, where it stops just behind the transmission crossmember, I know that it won't work when I move the crossmember back for the AX15. My question is, can I or do I use the downpipe from the XJ donor, or will that not work either due to length? If not, what would be the best way to remedy this? Next, I know that I need to upgrade the fuel pump when going from TBI to MPI. With that also comes replacing all the rubber lines with high pressure fuel injection line. My question in regards to this is, can I reuse the steel lines that are currently under my MJ or would I/could I use the lines from the donor XJ? Also, since we're on fuel pumps for the moment, will the fuel pump and fuel level floater (fuel sender assembly I guess it's called) interchange between the XJ and MJ tank? Will there be any wiring issues or is this not a concern since they're both Renix? Now, when I get ready to remove the drivetrain, I plan to remove the engine, tranny and transfer case all in one shot. How do I remove the AX4's "stick" or shifter arm to clear the belly of the beast? My MJ sits at stock height and I have only 2.5 ton jacks to work with here. Also, will the transfer case shifter linkages work when going from the 207 to the 231/242? I also should note that I have the shifter handle, linkages and brackets from the '96 XJ that the AX15 came out of. (Don't have the transfer case though.) Forgot to add, with the added weight of the engine, will I need to grab some 4.0 coils or will the 2.5 coils suffice? On a random note, I think my AX4 is an external slave setup. I was under the impression that early AX4's were internal slaves. But, the PO did say the engine was from a later model Wrangler. Perhaps the AX4 came from the same Wrangler? Just a guess.