Matching transmission to gears help

My dad has 3.91s on 22.5 lo-pro but he has an old school 13 dbl over .62 in the big hole. Turns 1400 at 65. Perfect set up for hill country

 

haha yea I had to do a double take when he said mack and then cummins. Blasphemy I say lol

Them shiny 290s could be made to pull tho

 

I think several options would help him. With 4.42 or 5.13 either one the spread on a 15 wouldn't be bad on it. That would get him up to a .79 overdrive. 15's are usually cheaper used cause not many like them because you can't split the top. However with enough under the hood or in the rear I think they work well.

If he has money and time find an RTO14609B pull the back box off of a RTO14613 and have a double over 13 with a good low hole as well as reverse but have the versabilty of splitting the top and really being able to roll for home if he wanted to. Keep in mind spinning the rears that fast long enough will make a little heat

 

My dad did exactly that. He loves the combo w/3.91

 

Idk where the p.o is located but I've got a 12513 id part with

 

would that give you a .62 od? My dad mis-matched 2 trans and has .62 for the last split. Would that technically be a triple od (.87 .73 .62)

 

Yes with a 14.?? Low gear I believe don't hold me to it.

You can run a RT14613 rear box on the RTO14609B and have essentially the same ratios as a 713 and 913. The top 2 will be .87 and .73

The RTO 13 speed aux sections make a lot of heat even with tapered roller bearings. Mine was good to strip the aux gear about every 100k. Even for all its trouble we sure had a lot of fun

 

My dad went threw and rebuilt it but it's deff a lot louder than the newer gen eatons. It whines in the big hole. With more power than stock going to it he usually only splits 8th

 

Stick an OD 13spd auxilliary section on it