The real question is if anyone makes them for the "Real 1-ton TRE's". When most people say GM 1-ton TRE's they are really talking about the 1/2-3/4-ton 7/8"-18 thread TRE's. 1-tons came with 1"-18 TRE's. Sky used to sell tierods and TRE's for the 1-ton stuff but he said he didn't have a consistant supply of the left hand thread TRE.
Part #'s for "Real 1-ton TRE's":
ES2011R, 1ton GM, 1" shank 4 inch long one (77-91 K30 obviously)
ES2064L Left hand Ford 1" shank, 4.75 long (77-79 F250?)
Sky will still make you the tierod for the 1" stuff but you will have to find your own TRE's. I think this is the better way to go anyways because you can return them easier.