The c-channel support plates were only installed on the 99 2388s. They were sort of a bandaid before the new cast supports arrived. The 2000 2388s were the first to come out with the heavy cast supports. I bought a pair of the plates from our IH dealer to put on our 98 2388. The plates costs $45 dollars for both. The heavy cast supports were around $400 a pair. Both parts are in the parts book. There is no doubt the cast supports are better, but if you take good care of your shaker bushings and bearings, the plates really beef up the old c-channels and should prolong the life of them. They both require drilling holes in tight places (right side) but it,s not to bad.