I have been looking at clutches, they list a 10" and a 11" clutch. If my truck has the 10", can i upgrade to the 11" with the same flywheel?

I do not think so. But I do not know much about manny trannys.

I thought I had read somewhere that the 11" clutch requires a different bellhousing...

if you have the miser version, you may have 2.76 rear gears, but with OD who knows.

You can check fairly easily.

First you need to determine if you have a sure-grip (posi) or open differential. Jack both rear tires off the ground. (Block the front tires!) Leave the trans in gear. Try to rotate a tire by hand. if the other tire spins the opposite direction, you have an open differential. If you can't spin the tire, or it turns but is

*very* hard to turn, you have a sure-grip.

For a sure-grip:

Jack both rear tires off the ground.

Make a reference mark on one of the tires and on the driveshaft.

Trans in neutral.

Spin one tire (both should turn the same direction when you turn one) ONE full revolution, while counting the number of revolutions the driveshaft makes.

Number of driveshaft revolutions = gear ratio. (e.g 2-3/4 turns = 2.76, 3-1/2 turns = 3.55, etc)

For an open differential:

Jack one rear tire off the ground (leave the othe on the ground).

Make reference marks on tire & driveshaft.

Trans in neutral.

Spin tire TWO full revolutions, while counting number of driveshaft revolutions.

Driveshaft revolutions = gear ratio.

I have towed with my '87 D150 with slant/904 & 2.76 rear gears. You won't be going anywhere fast, but the slant will pull the load. But I don't have a clutch to worry about burning up, and I have a torque multiplying torque converter.

How far do you have to tow, and will it be mostly highway, or stop and go city driving? If it's just a long haul, once you get going, no clutch worries, right?

-SM