What transmission will work best on a 454 engine in a 1986 Chevy 1500?

This vehical has an automatic transmission and also Im running 35'' tiers and do not use it to haul very much.|||if you are having problems and you feel the transmission needs to be replaced then replace it withone just like it or have the one in it rebuilt , the reason I say this is if you try useing anything else there are modifacations that have to be make before it will work right.|||It depends what you want to do with the truck a TH-400 is a very good heavy duty trans. if set up right but not practical for towing you can go to a junk yard and get a low mileage 4L80E (not the 4L60) it is a newer model heavy duty trans with overdrive and a tow mode you will only need to convert the electronic torque convertor lock-up mode to manual with a switch (which jegs sells very cheap) you can also use a 700R4 which has been beefed up with a towing kit it also has overdrive and a extreamily low 1st gear ratio you will also have to convert the lock-up mode to manual ....|||i would either use a TH400 or a beefed up TH350, one set up for HD use