On Monday, December 20, 2004, at 09:31 PM, prrk41361 wrote:

What are the visual differences between the AAR 70 ton introduced in
the early 1940's and the AAR 50 ton flat introduced at the same
time. Can the LL P2k 50 ton flat be used as a resonable stand-in for
the 70 ton car? Has anyone done this?

Brian,
In most cases the 50-ton AAR car is not a stand-in for the 70-ton AAR flat car. The 70-ton AAR flat car has not been produced as a plastic kit. Sunshine Models has produced some, however I didn't care for the NYC kit I tried to build as the cutouts for the deck didn't mesh at all with the stake pockets. I left the kit half built.

There are several primary visible differences between the two designs, including the 70-ton car having fewer stake pockets per side (one less per side on the 70-ton AAR design), shallower sloped fish-belly side sill, the wood deck has five sections with a steel "T" (flush with the top of the deck) at each bolster to the end sills instead of a continuous wood deck extending the entire car length, and different location and spacing of the underframe crossbearers and crossties.

An notable (but unmentioned) model railroad company received general arrangement and brake arrangement drawings of a number of 70-ton AAR cars about 5-6 years ago. These happened to be Greenville Steel Car Co. drawings since GSC built a significant number of 70-ton cars for several railroads plus kits for B&O's numerous 70-ton flat cars built at their company shops to AAR standards. However, to date the project hasn't materialized for reasons unknown to me. I personally hope the interest will be rekindled.
Regards,
Ed Hawkins