Here's a question for those of you that have some experience in this area. I have an 01 4x4 auto tranny with 3.54 gears and 305 tires (which takes the effective ratio to approx 3.42) I sometimes pull my 5th wheel toyhauler that comes in just under 12K empty and probably about 13-14K when loaded. Truck does fine on the flat and okay through the Sierra's up Hwy 80 towards Reno. Though some of the longer and steeper hills do slow me down to 40-45 mph. Recently I pulled a pretty steep grade that due to the narrow winding road allowed me to start at around 30-35 mph but quickly slowed me down to 20-25. Biggest problem was that both the truck and tranny overheated before the top. I was able to pull over moments after the lights/gauges went off and let her cool down before continuing.

My question, where would my $$ be best spent and give me most bang for my buck? Upgrading the the TC and valve body? Or, changing out the gearing to get an effective 3.73 or so ratio for better towing? Neither is cheap but the tranny work is a whole lot more. I can swing one or the other but not really both at this time.

 

If your trans is stock, I say do that first. A tight converter will pull better.
With those tires, I'd like the 4.1 gears too!! I had 305's on mine for a while and didn't like them, even of flat ground. I have the power, but the gear spread was bad for 3-4.

 

I'd do a VB/TC. If you overheated the trans, you need to flush out the fliud anyway.

 

I vote the tranny also. If you were down to 20-25 MPH the converter was likely unlocked which is a real quick way to burn up your tranny. A lockup switch would be a huge improvement.

 

Another vote for tranny.

 

I figured the tranny was the answer. Groan. Not cheap but I have it scheduled for an upgraded torque converter and valve body in about 2 weeks. Better than sitting on the side of a mountain hwy with a roasted tranny waiting for a tow$$$