I hammered the floor a little, it honestly didn't make a difference as I was unwilling to hit it hard enough to really force it up. Was more just to gain an extra 1/4 inch.
Yes, the Gear Vendors is a remade Laycock De Normanville overdrive from behind a Volvo.
Those are smaller type J units. The GV we run now is a Type P, which is considerably heavier duty.
I've known people to hunt down the older units, but I've also heard of them breaking behind fairly stock engines.
If ya wanna play, ya gotta pay, I'd buy a new one for another vehicle without hesitation.