[Lynn Eades]

Rob, I wondered if the shims were because of a bad manufacture of the steel top hat sections, but there could be many reasons for things not lining up.
I'd suggest though that most likely the problems are around the front mounts (or at least that is where corrections have to be made)
I see in my 1941 to 47 chassis parts catalogue (Ford) two insulators listed;
1. 51T-6038-C
2. B-6038-C this is the same part no. insulator as in the early Canadian carrier parts book.
In FUC-03 the insulator is listed as;
09B-6038.
Macs sell an insulator on its own. 78-6038-S
They sell two mount assemblies:
1. B-6038-S. This one has the big steel cup washer that has the 1 1/8" hole, that is correct for the carriers. (washer part number 78-6048-A)
2.B-6038-C this one is the correct part number (for a carrier) but cup washer is wrong (small hole)
I don't know if the insulators are the same
Lastly the jeep has a similar looking mount supporting the transfer case. This one is part number 74-6038 It is possibly a softer mount.
Dagenham (U.K. Ford made their own mounts as well, but I cannot find any British part numbers. I do have a Ford script one with made in England on it and a patent number.

Do not forget the large dia. flat washer that fits directly under the water pump foot and on top of the insulator. This one spreads the load on the rubber as the insulator is compressed.
At least one of the other big suppliers (Early Ford?, C&G Ford? sells the parts separately. I bought mine there, but forget who it was.
I know Mackays rubber in Australia made these mounts for many years. No doubt many other rubber mount manufacturers copied them as well.
Some of the mounts are made with a steel base molded into the rubber. Some are flat on the bottom, while some have a shallow hollow underneath.The Ford 74-6038 has a deep hollow Some only have the outer ring of steel molded into them.

I guess the whole point of this post is that you have to be a bit careful to try and get the right parts. Many off the various mounts may have been produced with not too much care (or need to care) if a mount they made was an 1/8" too high or low at assembled height. Most Ford cars and trucks have rubber mounts at the rear and were / are more forgiving, by design, than the carrier.
At the end of the day, an extra washer between the water pump and the insulator will likely fix any discrepancy.