J turns trash transmitions, not just syncro ones. well more to the point it killes the reverse ideler so if you liek your car droppign the clutch in reverse is a bad idea. other than that drivetrain wont mind that much. as for the handbrake qusetion never actuly woked out the defanate answer, i don’t think the handbrake warngin light switch connects inthe the syncro loom so i dought there is anythgin engadgeing the freewheel so dont think it would be optimal to try handbrake it. it may try and work as a 4 wheel handbrake through the transmition that’ll give the frount diff a bit of what for, but don’t think the rear drums would provoide enuff brakeing force to actualy damage anything. it’s hump back bridges + full throttel in 3rd that really don’t mix
