Thanks to AMT that it has issued this kit some past time. Now the kit  will serve in pair, as two important items in the diorama. I got one kit from ebay, and headed on manufacturing the second by resin copying the kit. The hardest part seemed to be the track shoes because there are 84 of them in one kit. That was a new challenge for me- this would be the first time I ever cast such big items. 

UPDATED Dec.14,2000:
I began with a trial mold made from 5-minute silicone putty. I cast a sample piece, but the joint pins readily got broken due to brittleness. So I made another trial, this time I used polyester filler putty. I put a metal insert as the pin from a piece of paper clip. This proved fine, the putty stuck to the pin and firm enough for a model.

I repeated casting with resin, with the metal inserts. Still fine results. To make better grips, the pins were roughened with filing. Here, you see a cascade mounted. 
And here, a cast one is placed in the kit's original tracks.
Heading on for better parts, I made a new mold, enabling good command on poured resin.
And here is a sample from that mold. Following parts were better.
UPDATED Dec.26,2000: 

The geared wheels were resin cast by the aid of a RTV silicone mold.

For the piston rod, a 2-piece mold was made from 5-min. silicone putty. Instead of copying the whole rod in resin (which had a risk of breaking), I put a polished steel rod in the mold and cast the head with pins only. Nice job!
The big roller wheel was copied by making an open half-mold. The one on the right is resin, and on the left is automotive polyester putty. Both resulted in good pieces, but the one from the putty had some gaps on it, since it was not liquid prior to putting in the mold. But those holes can be filled easily, so it was no problem.
Here, the two are joined by superglue to form a wheel unit.
UPDATED Jan.10,2001:
The hood was done with foil-copying and using it as a mold.
My resin stock ended, and not being able to find the brand I used, I tried other materials for casting. The molds were made from silicone mold putty from here on.
These parts were cast from 5-minute epoxy. Took a few days to harden fully.
So were these transparent parts, except for the dark gray ones below. They were done from metal epoxy. The white styrene pieces you see within the cast command console are embedded in the resin fill up volume and save resin.
This left outer wheel and track holder was cast from the last remainders of resin.
The pulleys and belts were duplicated by using automotive polyester putty. The difficult part is that since it is not liquid, you cannot be sure if it goes to every point in the mold. Here you see on the left small pulley, an empty part. It was later repaired by adding putty, too.
Now coming to the engine.. The sides were cast seperately and then joined. The purple ones are the molds, and below them are parts cast with polyester putty.
The crankcase and rocker covers were cast from another brand resin (fillers also used here as seen..), and flywheel housing was cast from polyester putty.
Here the copy is glued together and placed in front of the original. Since I bought the original kit assembled, I could not disassemble it to every detail, which made mold making harder.
UPDATED Feb.12th,2001:
The two engines assembled side by side in the following two pics.
The one on the left is the copy, the other is the original. The starter motor and lower radiator hose are missing on the copy, they were mounted later.
The outer wheel holder was copied with resin, this time a transparent one. The paper clips embedded are for rigidity purpose.