We used one of those push rod tubes on our '84 GL 'cause it had a pin hole
leak in one of the tubes and was dumping oil all over the ground.  Bought two
tubes from Ron at the Bus Depot.  We only installed one (that solved the
leaking problem) and it was easy and works great.  I thought maybe you could
remove the rocker assembly and then put it back on without re-adjusting the
valves but I couldn't (the motor was running on two cylinders).  After I
readjusted the valves the thing has been running great ever since.
Pick this time for an oil change as most of it will be coming out anyway.
Have fun.
Ken Wilford
John 3:16