CB Performance use to carry HD torsion leave kit's, but only have the stock ones now. If you have ride height adjusters on your beam you can "preload" the upper one and get a stiffer ride, and if you don't like it... it's way easier to change back than the whole leaf stack.
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1970 T1 W/MassIVe 2913cc RAT/?EFI? w/direct fire (very soon) and 915 trans
1962 SC 1776cc SP 944NA brakes, 993 wheels
VKG