Steve and Barb Hile
I know that Richard Hendrickson consulted with Life Like on their Proto 2000 tank cars, so I would be somewhat confident about the numbering and lettering. But…
The car would definitely not be an X-3. That was the UTLX design. On the end, where X-3 is, it should be a letter Z. That was UTLX’s designation for cars that were not its own design. (XM is, of course, a boxcar.)
The other problem is that cars in the 60000 series were, generally, insulated. So, according to a 1952 listing of UTLX cars, which Richard provided to me, years ago
60350 was a class Z car with a 10000 gallon capacity, but it was also insulated, which the P2k car is not.
I hope that this is useful information.
recently purchased an older Life-Like P2000 kit for an ACF Type 21, 10kgal
car. It is pre-lettered as UTLX 60350. The number seems quite
plausible based on the 1930 and 1935 OEREs, and on Union's
propensity for buying up other fleets in that time-frame.