I found once I made it to the low 12's I could not keep a muncie in the car for more than a week or two before it failed, broken gears,cracked cases, put a auto in your big fat car and go faster with little to no problems, the switch in my car gave me a half second with no other changes except a swap to the 400. Banging gears is great untill you break it, I got tired of always being down. The only other alternative would be to go to a high quality manual transmission!
Mine has the stock two piece in it as well, mine was four speed for years, but I eventually gave up, do you have the stock rear end as well?, and how does it 60 with your launches, mine will 1.50 wheels up, never would do that with the muncie!!
mine has bested 10.64 at 126mph
Well I was just making a suggestion, I could never get consistency with a four speed in my car, and I also had to put a 9 inch in mine as well, I really didnt want to go with an automatic but it worked out for the best and I have had to do zero maintenence on the drivetrain since the swap, also never won anything with the 4 speed but you cant beat the cool factor of banging gears!
Liberty Gear does all the face plating. Everyone else basically just installs the parts they get from Liberty. My only advice is to take what ever time frame they give you to get it done and double it possibly even triple it.