I would ask your tranny guy about a 4l80e swap
A stock 4l80e is already 1 ton rated
Your building a 1 ton I would think you will use as a 1 ton load wise trailers campers etc .
4l60e is a light duty 1/2 ton tranny
As Clinebarger stated in a tranny thread
He can build a tough 4l60e for about $5000
Compared to a built 4l80e for about $2500
http://67-72chevytrucks.com/vboard/s...d.php?t=812006