There are so many things wrong with this situation I don't know where to start. Ignoring the fact that they changed the frame layout as opposed to simply designing a different mount when a component was revised, as BMW has already done many times over (think M30B32 vs M30B34 or G265/6 vs G260/6), this is not a large problem to overcome. It's actually surprising to me that anyone would even bother to manufacture the old chassis when the new one seems backward compatible due to the slots. AND, the new frame is backward compatible to a component that's not even rated for it (in NAS trim). Further, what's actually different is a overcome with a shade tree modification. a hack if you will, so what's the point anyway?

 

I've done several HP24's into older 99-02 D2's and I don't remember doing a lot of mods to get them in there. All of them were friends D2's with dead HP22's and at the time HP24's were all over the place in LKQ 03-04's with dead engines.

 

Good to know. I'll move forward with the project and report back my findings when I get relevant info. Don't hold your breath, there are a couple other projects in front of this one.

 

Well, moving forward didn't take place exactly how I planned, however, here we are 2.5 years later and the trans is in. Having a good trans jack is critical, as is no surprise. This one is able to handle the 400+ pounds of the trans/transfer case and torque converter, and has the ability to tilt back and forth as well as side to side via two separate handles that are driven by a 1/2" ratchet. This made lining the trans up to the engine face a piece of cake, and I was able to literally roll it into place and tighten the two long bolts at the bottom with my fingers. This also satisfied my concern that the torque converter was on all the way too.



As for the trans mount points, as everyone suspected they do not line up. The 4HP24 is indeed a half inch or so longer. This isn't a big deal on the passenger side, I used a die grinder to elongate the slot and moved the trans mount back to bolt to the bracket on the trans. This was right after I started.



The driver's side is going to be more of a challenge. The trans mount is in a much smaller pocket and even if you were to elongate the slot, the mount will hit the side of the bracket before you can move it far enough back to line up with the bracket on the trans. More on that later.

 

The driver's side required a lot more creativity. I don't see how this swap can be done without accommodating the different mount points. You can't simply elongate the driver's side slot so I had to shave about 3/8" off the aluminum block on the trans mount so it could shift rearward in the frame bracket, and drill/tap a new hole for the stud. I'm not an engineer but I'm not too worried about the structural change. I could always drill the bracket and go back to the original stud location but I don't think that's necessary. Apart from the two mount points there were no other surprises. Well, I was really surprised that the 99 did not have a CDL transfer case in it.



Torque converter/flex plate were the same so there there was nothing at the front to worry about. The rear driveshaft from the 4HP24 was in fact shorter so I used it, but I would guess either would be OK due to the splines making up the difference. I used the trans sub-harness from the 4HP24 because it accommodated the different switches better and if someone wants to put in a CDL lever then it will report back to the cluster properly. As mentioned there is no internal solenoid lock on the 4HP24, and there is no linkage solenoid lock on the 99, so technically you can select Hi or Low at any time. Not an ideal result but not too scary. I was really surprised that the 99 did not have a CDL transfer case in it.

Of course the XYZ switch turned out to be bad so I had to put the switch from the 4HP22 back in, that would have been much easier with the trans out. The original one (black) did all kinds of crazy things with the PRNDL lights on the shift lever, and threw a code immediately along with blinking M&S. I went through the codes and reset the adaptive values for the TCU, hoping that would help, which it didn't, and then replaced the switch with the one from the the 99 (gray). Slowly I moved the lever and all was right through P R N, until I got to D. Blinking M&S on and blinking D on the lever, and no lights at all on 3,2,1. I cursed my luck and started reading up, and pretty much right away hit on the "low battery charge" likelihood. The truck had no problem starting whatsoever so I was skeptical but I put a charger on it and it jumped to about a 6 amp draw. It topped up in an hour or two so I was still skeptical but when I restarted the truck the shift lever worked as it's supposed to!

So now I'm close to the finish line. I still need to refill the trans, and if I ever meet the guy who decided that removing the disptick/fill tube was a good idea he's going to regret it. The jury is still out on the electronics, for now I'll leave the TCU and SLABS alone but I may swap them at some point just to see if there's a noticeable difference. The donor ended up being an '04 so it should have the best stuff.