The GMC CCKW

So the gear oil was everywhere, getting transfer case down is one man job providing one use hydraulic jack, few planks and common sense, getting it from below vehicle is only just one man job. Transfer case is much smaller then gearbox but much more heavier so be careful.

Original seals are steel boxy shape with leather seal and felt ring, size 2x3x¾ inch, getting them out is simply hammer and destroy affair. NOS can be obtained but my experience with sealing components which has been on the shelf for half a century is not too enthusiastic.

I have managed to locate standard rubber seals size 2x3x3/8. I have installed them in pairs. Since outer seal probably will be getting very small amount of oil in between seals I’ve put a lot of synthetic grease. Also having transfer box out I have replaced all paper gasket with teflon paper and silicone.

Installing transfer case is a definitively two man job, I’ve used ratchet straps and hydraulic jack, the only difficulty is getting in between frame crossmembers since the case has to precise positioned, otherwise it will not fit.

All in all replacing seals and gaskets takes around three afternoons and some muscle effort, apart from standard tool the 1 ½” (38 mm) socket is needed.

I sincerly hope that there will be no need for getting it out again in foresable future.

I regret to inform you that taking it out is quite easy:

Disconnect everything. Remove a bolt on each side and insert a prick punch. Remove the rest of the bolts. Place a tire only under the xfer. Place a piece of plywood on it. Pull both punches. Just like a nelphant having a baby!

You should use M211/M135 seals. They WILL NOT LEAK!!!

To reinstall: Connect the upper rear drive shaft with the unit on the floor. Move the rear wheels so that the U-Joint is like a T, not an X.
Take a pair of welding clamps and clamp the brake band to the drum. Place a floor jack under the lower read U-joint flange. Place anothe floor jack under the front driveshaft U-joint flange. Alternately jack the two jacks. The clamped brake band will only allow the xfer to tile front to back, not side to side. Once the xfer enters the frame mounts. take a regular bottle jack and lift it into place. Put a punch in both sides for safety. Juggle around till you can put the bolts in.

This works quite well on the banjo. I think it will work on the splits well too.