The longer pin is only needed if the reverse input drum (the part the band engages) has been turned down. I personally find the pin useless simply because turning the RI drum down is a bad idea. It's cheap, if you're inside the trans just put a new RI drum in it.
Corvette servo helps on the 1-2 and 2-3 shifts only (and is a recommended part... install it!). For towing you should add the sonnax 4th servo. And with 100k+ miles, put a sonnax .490" boost valve in it... gives a little more pressure over stock and by this mileage the stock boost valve is worn and leaking. Meaning it isn't putting enough pressure on the regulator valve, giving you lower average line pressures.
The three things that predominantly kill a high mileage 4L60E are: worn boost valve (drops line pressure), cracked/leaking 1-2 and/or 3-4 accumulators (stock plastic pistons crack and drop line pressure), and a worn out PWM circuit for the torque converter (drops line pressure). The final result is almost always a blown direct clutch... meaning no 3rd or 4th gear.
Corvette servo helps on the 1-2 and 2-3 shifts only (and is a recommended part... install it!). For towing you should add the sonnax 4th servo. And with 100k+ miles, put a sonnax .490" boost valve in it... gives a little more pressure over stock and by this mileage the stock boost valve is worn and leaking. Meaning it isn't putting enough pressure on the regulator valve, giving you lower average line pressures.
The three things that predominantly kill a high mileage 4L60E are: worn boost valve (drops line pressure), cracked/leaking 1-2 and/or 3-4 accumulators (stock plastic pistons crack and drop line pressure), and a worn out PWM circuit for the torque converter (drops line pressure). The final result is almost always a blown direct clutch... meaning no 3rd or 4th gear.
