Your gas mileage is good, you don't need to do anything. It will be many years before you get the modification money back on better gas mileage. Do the math. How many miles per year, in town and hiway. Realistic expected mileage improvement. Price of gas per gal.
10,000 miles per year.
average 18 MPG @ $3 per gal
Improved average 21 MPG @ $3 per gal
Delta savings $238 per year.
Good Reman NV4500 $1800
All the other stuff $900
Labor $1500
Total $4200/238= 18 years amortized
Cut out the labor, it's 11 years. At any rate it will all be worn out by then and need done over again just as you get even
I'm guesstimating of course. Just an example using some of your given info. Use your own numbers and everybody will have numbers also.
You don't rebuild a SM420, they are a dime a dozen as well as SM435. $150-$350. New throw out bearing $35.
A 700r4 will solve all your mileage wishes, no clutch to worry about hooking up and you can have a floor shifter stick that looks like your Sm420. Piece of cake install. Much cheaper. Faster off the line and nice to drive.
