swap in a 13?

So to change my 3406e from a rtlo15610b to a 13 or 18 need to redo the drive shaft as well?
Got 3.80 rears if I remember right lp 24.5 would I get any advantage upgrading?
Right now low 5's summer low 6's running at 65 close to 1600 rpm.
Sorry OP did not mean to hijack just thought since it was talked about I would ask.

 

just gotta say, very nice truck Rank, would love to own one some day.

why would you want to get rid of that bug 15 speed? they don't make those anymore hahaha We had one in our 1990 379, we loved it.

once again, love the truck

 

I went and looked it up rank, they're the same length

http://www.roadranger.com/ecm/group...er/documents/content/rr_rrsl-0001.pdf#page=16

 

Well if you do 70k miles a year the difference between 6 and 6.5 mpg @ $3 a gallon is $2700.

So almost 2 years.....

 

Can you post the exact model trans you got? It might be a .84 overdrive.

 

Yeah.. the 9s (except for the "Cs", e.g., RTLOC16909E, etc.) and 10s have a main box and an auxiliary... 8LLs, 13s, 15s, and 18s have are compounded with another auxiliary box.

Good call. From what he's saying (running ~65 at 1600/1700 with 3.90s and 24.5s), that matches up more with what a .84 - .87 OD transmission will do than a .73 - .78 OD.

If anyone wants to know how to calculate these things, it's (##60)/(B*C*D)
A = engine RPMs
B = transmission ratio
C = rear end ratio
D = tire revolutions per mile (476 for 11R24.5s, 481 for 295/75R24.5s, 468 for 295/80R24.5s)