The one on the right is the original clutch arm off the Isuzu I am putting in...but the extra length above the divot is causing an interference with the exhaust crossover. The one on the left is the one removed from the Muncie 4 speed that came out of the car. Are the positions of the divots close enough for this to work, or am I better off modding the arm from the Isuzu? Was there another arm available for the Isuzu that would be a better fit? Anyone have one?

Not a problem. I shortened one on a Fiero a full inch last year, looking for a faster ratio. We couldn't tell the difference.

Use the cast one. They're much stronger. GM switched the isuzu to those later in production anyway. I posted pics in the trans identification thread if you want to see first hand. Direct comparison of an 88 and an 85 isuzu's. INteresting differences for the exact same trans. I do not know if there is a difference in size between the 4 speed and isuzu ones though. Too bad, I just sent mine to the crusher (shredded 2nd gear).

When I installed an Isuzu in my '86 GT, I cut the top part off the stock stamped steel arm until it cleared the exhaust system, and then rewelded it (sorry, no pictures). It works fine, but just be aware that the cup is made of teflon or plastic so either remove it before welding or use a MIG welder to control the heat.

CowsPatoot
I think I still have a 88 Izzie arm if you want me to look.