Our 42 is a 1998 that is painted, (first year for paintIJ) The 18" extensions I bought at that dealer auction was dumb luck at the time. I bought a set of galvanized ones on a pallet, 1. they were galvanized so if I had to modify them to fit our machine, they would be less likely to rust. 2. The galvanized ones were going cheaper than the painted ones. 3. All the support rods were tucked neatly under one of the panels! We got them home, but had to wait for a rainy day to install them. Not knowing if they were going to work, I used a tape measure and was surprised the measurements matched up. The next surprise was all the holes on the hinges lined up with the holes in the machine for the rivets to go in. We added a couple extra in a place or two, but it was an easy addition. Took less than 1 hour for two of us to do it! Now from looking through older pictures and brochures these appear to be off a early R50. They are the taller ones. There looks to be a 12" available. That must be the difference, in the brochure on grain tank capacity. Take the extensions off an R50-52 and it would be a 170 bushel bin. Put the 12" on and you get 225 bushels. Use the 18" extension you get 245. I did figure this out when I installed them by calculating the cubic feet I was gaining for our 42. Then mulitplying that number by 0.8036, I came up with about 68 bushels. The 18" extensions came with curved panels on top of them yet, I suppose to heap it up to the 245 capacity, but I did not use them. The 18" was way plenty for what we needed. Made our combine look asthetically better also. Oh I did call a dealer to ask what a used set of extensions would cost. $385!!! That $50 spent turned out to be a very good investment.