Well- - - -I did take one trip down the grapevine in 1976 with a 78K gross weight and no brakes. No ice, and only one trailer! 28 seconds between mile markers figures out to 122 MPH or so. No, I was not driving a twin stick rig that night- - - -just an Eaton 15 speed. That's a 5 speed main box and dual 3 speed electric shift rear axles. They're actually only 2 speed axles- - - -to get the "intermediate" ratio one axle shifts to low range and the other to high- - - -and the planetary inter-axle power divider makes up the difference! I think the engineer who designed that system was R. Goldberg! Also- - - - -the Cat 1674 engine in that 68 Freightliner did not have a Jake brake- - - -as there was no way to install one on that design of engine!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!