external reverse question

[x-bird]

Both of the engines i picked up have external reverse. on the top and bottom of the outer case of the reverse gearbox are threaded holes. One case does have a bolt in the top hole. Are these supposed to be adjustable stops for the eccentric inside?
Not that i think it matters, but the gearboxes are identical internally, externally the one of the sunl looks to be earlier as it's a much "cruder" casting-- it's black while the rest is silver, almost looks more like an add-on whereas the carter's (a SYM engine) is silver like the engine and has a much smoother and contoured exterior.

[SYCARMS]

The older cast ones I believe were better and took more abuse. The holes you speak of sound like the access holes to gerase the unit. There is no adjustment except for the cable.

TOM