It's telling that Frank's reaction to the Tangent announcement was enthusiastic. Two quotes from his email of last Friday:
"WOW have you seen the new Tangent 8K GATX acid cars."
" Boy do we have the kit-bashing possibilities here!"
These are very compatible products, with both kit-bashing and kit-mingling possibilities. The 8K Tangent isn't in hand to permit comparisons, but these photos show the possibilities with the Tangent 6K tank. (Note - there is some perspective distortion in the photos. The tanks are all the same diameter, and the 8K RCW tank and frame are 4 scale feet longer than the 7K.)
Photos comparing RCW 7 & 8K tanks with the Tangent 6K:
The RCW 7K and Tangent 6K are the same length and diameter, the difference in capacity due to the lost volume between the pairs of bulkheads separating the internal compartments in the 6K.
Here is an assortment of frames:
The RCW frames are cast in two-part molds with detail top and bottom. Marty commented on the minimal amount of flash - the two in the photo are random ones I grabbed off the pile, and the flash is typical. The stretched Tangent frame is a replacement for the Sunshine part, but requires two complete Tangent 6K frames plus some other parts. Whether the new Tangent 8K frame can be backdated with Archer rivets to be a better choice remains to be seen. (I have two Tangent undec 8K kits on order.)
So we're going to have both ACF and GATC underframes available, each in two lengths. This is about when Richard would jump in and comment on how much tank swapping took place, and when, The 7K RCW tank will certainly fit on the Tangent 6K frame, and the 6K Tangent tank on the RCW frame. At this point my knowledge of the prototype runs out.