2.73 rear end
 

I recently acquired an unfinished project, '81 jimmy that has been converted to 2wd. It has no engine or transmission. I just checked the rear end ratio by jacking up one wheel and spinning it 2 revs and was surprised to find it's less than 3. I checked the net and found that there was a 2.42 and 2.73 available. I believe mine is 2.73. Now I'm trying to get my mind around the best engine/transmission combination to look for. Does anyone out there have info on what was used originally on trucks with this rear ratio? I plan to make a driver, no racing or towing, but I do have some hills to deal with. Should I start looking for a different rear axle? Any suggestions will be appreciated.
Thanks.

Re: 2.73 rear end
 

If you are running a T350 or T400 and V8, then that rear will be a nice cruiser. But, it will lack any omph from a dead start. If you are doing a OD style tranny, then I would look for a 3:42 or 3:73 rear gear for it.

Re: 2.73 rear end
 

Use one of the online RPM calculation sites. Feed in your rear end ratio and tire diameter and get your engine RPM back. Since you are after a driver instead of a load hauler, a smaller tire might be a simpler answer then a rear end change.

Re: 2.73 rear end
 

The very low ratios were usually paired with the straight six engines. Those engines are torque monsters, particularly right off idle, but they don't rev high. I would look into a built 292, with an emphasis on bottom-end torque instead of HP. It should feel and drive similar to a diesel when all's said and done. A manual transmission will make it all the better.

I'm driving a bone-stock 1981 2wd f150 with a 300-i6, four-speed manual, 2.73 gears, and 28" tires. It's a hoot just tooling around local country roads. The bottom-end torque is unbelievable, and fuel economy is pushing 20 mpg on longer trips.

Re: 2.73 rear end
 

One time at the dealer (1975) we got a brand new plain jane C20 in off the transport. I got to drive it downtown to the showroom/shop. It had a four speed manual and it had so much power that as soon as I got it into the setup shop, I jumped out and popped the hood to see what the heck monster engine that it had in it.

Danged if it wasn't a 292 straight six! :) We obviously didn't see many of those. And most of the new vehicles ran like crap because they hadn't been adjusted for the altitude yet (Colorado Springs).


Actually, I would love to swap out the oil burning 350 in my 76 GMC for a 292 ;)

My friend down in CO has his dad's old 1965 K20 with a 292. Only vehicle in the world that I'm jealous of :lol:

Re: 2.73 rear end
 

my 86 had 2.73s.. it came with a 305/sm465
but like stated..work the gear ratio around your engine/trans/tire combo

Re: 2.73 rear end
 

My dads truck came with the 2.73s. 1982 1/2t shorty. Engine----6.2 diesel with a 700r4. It has been changed out

Re: 2.73 rear end
 

I've had 2.73 and also 3.08 in multiple trucks with a 27" tall tire
Any decent engine will pull the gear all day and get decent mileage.

Re: 2.73 rear end
 

My 85 had 2.73's and a 700r4 from the factory.

I swapped in a TH350 and even with a very stout 383 it was pretty underwhelming off idle (28 inch tire). Now with that being said it would absolutely cruise down the interstate pulling my boat at 75+mph.

I swapped cam/convertor and went to 3.73's but I have to admit that I miss the 2.73's on the highway. Its a fantastic ratio with a 3spd auto if you just want to drive down the highway.

Re: 2.73 rear end
 

My 77 burban had 3.08s . With the anemic mid 70s motor and tall gears felt like it took forever to get to highway speed . Living in the north east it was fun hitting some of the mountains at 75 and mashing the pedal down and without even pulling a trailer I'd below 55 at the Crest. But it was nice to cruise at 80 on the flat lands

Re: 2.73 rear end
 

2.73s were the standard axle for 6 cylinder vehicles in 81. a 2.56 was the standard for V8s. Most v8s were optioned with either 2.73 or 3.08s. Again plan around what engine/tranny and tire combo you have and what you want.

My 81GMC C1500 is a 250 six with T350c and the 2.73 rear gears. It does fine, but definitely not a hot rod off the line.

Re: 2.73 rear end
 

I have an 84 with a 305/350 2.73 from the factory. Just swapped it out for a 3.42 and love the pep it gave in the little motor. I do suspect it will be a bit less comfy on the highway, though.