Bonjour
After running with a failing viscous coupler in a 1997 Grand for over a year and stuggling to park the vehicle without it bunny-hopping into position, I elected to either replace the VC or the case.
Considering the VC was about £200 groats + shipping from the US and I could source a nice NP231 (command-trac) or NP242 (selec-trac) for considerably less, I chose to source a replacement TC. Sure enough, a 231 off a 1997 Cherokee turned up in West Ealing for £50.
The Yanks do this procedure all the time, it seems - according to the forums.
The swap took a couple of weekends, as I wasn't rushing. Removing and dropping the old 249 wasn't that bad ......I only weigh 10.5 stone and am not especially strong
The input shafts had a different spline count (21 vs 23) so had to strip the cases down and swap the input shafts. It was useful exercise as I could see the condition of the new case and it looked new inside with minimum deposits on the magnet. I ordered a NP231 seal kit from the US and fitted a new transmission output shaft seal to the back of the transmission and new seals at either end of the transfer case.
After refitting, the shifter mechanism needed no adjustment and driveshafts connected up without issue.
The net result, is the car being driven in rear-wheel drive and moving with much less effort. It also goes around corners and parks like greased weasel-sh*te. I'll try and source a new shifter command-trac surround.
So if anyone's mulling this procedure and has somewhere where they can leave their car with the back of the transmission missing for a while, I would recommend it.
G.
