converting 9 speed in to 13 speed?

Had that setup in 92 379 425 cat RTXO14613 (had straight shift pattern) not real big HP but not bad it put 592 on the ground at st Louis cat house on 70 west. very fun truck to drive

 

I just bought a conversion kit tonight at Freightliner dealer in St. Louis and it cost me $120.00, I have a 9 spd but seems the gears are just too long in them. When you pull long grades it seems either lugging too hard or wound up too much. Hoping this will be the fix I need. The part # if you want it is, FUL K3538.

 

I'm looking at a big cam 400 with a 9 speed transmission. The truck has 3.90 gears, can I put the box on the back to make a 13 speed and drop rpms for better speed and not running engine too high rpm? Any knowledge would be appreciated.

 

I converted few years back. Around $500 for parts and labor at volvo dealer.

 

Need to know what the model number of that trans. Some can be converted cheap and easy, others not so much

 

I have a 2007 Volvo d12 @365hp runs 60mph at 1500rpm in 10th (last hole). 3.08 rears. Need to be able to run 70 comfortably. What’s best option? 13 speed swap ?

 

By the sounds of that you have just a direct 10 speed (no overdrive gear) so going a 13 speed transmission with overdrive will give you more speed at the same RPM,(all things the same this would be at 80mph in top OD @ 1500rpm and 70mph in lower OD @1500rpm) but with those 3.08 rears and 365hp pulling power is going to be a real struggle in overdrive with any weight.