converting 9 speed in to 13 speed?

Couple of times, I could have used an extra gear or two on the low side. Called a friend who has a little more knowledge than I about this, he wasn't to keen on this type of conversion, and not able to talk long, but he said something about an 18 having bearings and a 13 having bushings may be the reason that the conversion wouldn't hold up like a factory 18.

 

Look at the tag on the right side of the tranny, see if it's RT or RTO. If it's RTO you don't need any thing else. if it's RT it will be easy to convert and will give you .87 overdrive if you want 13 sp. RT is 1 to1 in 9th, RTO is .73 in 9th, witch is the same as 99% of new trannys

 

surly it's a RT14609, you can put 13 back half on it, it will give you .87 overdrive witch is still slow. probably for a few more dollars you could find a 10 sp. a 15 over will .79 over but still the easy way to speed it up would be later 10sp they have .73 overdrive.

 

Why not turn 8th and 9th around, add the back box and make it a double over 13 speed?

 

Loose you low hole and very few trucks can pull out .73 overdrive much less .60

 

Dont think you will loose the low hole by turning 8th and 9th around. But the truck he is buying has 4.11 rears. If it had 3.36's I would agree a .60 overdrive would be to much.
Back in 1990 I had a truck with 3.70 rears and a 13 doubleover and it was like having the best of both worlds...pulled grate and had a nice top end speed without running the RPM's way up.