First, i want to say that i want to, and believe in, doing things the right way and not 1/2 assing things.
1) Background info:
a) Truck is: 1/2 ton 2wd, 4.3 v-6, TH-350, 2.56 rear diff (i know, TOTALLY wrong for towing and we'll get into that)
b) i want to tow no more than 5300 lbs. (open 14' trailer, "small" G-body/monte carlo etc.), but usually 3900lbs. (open 14' tandem trailer w/ chevette with small block with iron heads)
c) i DO NOT, at this time, want to buy another tow vehicle because of space---already have too many cars, and i want to curtail spending. Although i have not ruled this avenue out 100%, if it's the best way and i certainly can do it budget-wise, although i really don't want to.
d) The 4.3 v-6 has a very similar, if not identical, torque and hp curve as the LG3 305 that was in the truck previously. The 305 combo did not do too well towing even the chevette, hence my asking the question in the first place. The crate 350 that was in the truck before the 305, i feel, could do the towing job pretty good(even though i never towed with it) and we'll get to that in a sec.....
e) i do not plan to tow long distances. Only to local tracks. So, maybe 1-2 hrs away max.
Logic/illogic:
a) As i stated above, the 305 did not do too well towing even the chevette. The truck handled the trailer pretty good and the 305 did ok on flat ground, but even the slightest incline made it slow down. i noticed real quick how much truckers are in a hurry on the interstates----because those guys were on my ASS. This was very mentally uncomfortable for me and my main reason for starting this topic----i want to reasonably be able to keep up with traffic.
b) i like the 4.3 and want to keep it, although getting a crate or vortec L31 350 is probably the simplest, cheapest, most intelligent way, in my situation, to solve the problem. And is certainly do-able budget wise. i'm pretty sure either 350 will have no problems towing 5300 lbs. all day. The truck has had 3 previous v-8s, so i have all the mounts, exhaust, odds and ends etc.
c) i have never done a differential gear change and am not opposed to doing one. This may be cheaper than b), but not necessarily the most time-efficient----the truck may be down for a long time, because i WILL get stuck and will have to ask for help here and on many other sites. i would want to go to 3.42 and not any lower.
So, i'm thinking if i left the trans in second; 1.52 x 2.56 = 3.89 final drive AND 35 inch tires would be 2600 rpm at 65mph, which i think is ok.
i guess the bottom line is :This strategy may be kinky, but is it feasible?
When i'm not towing, i would just switch back to the 29 inch tires and drive in "D" like normal.
The other approach would be to tow just as is. Maybe try to tow later at night when there is not much traffic.