'72 Chev long horn,3/4 ton,350/auto NEED REAR END INFO

[oldasi]

Have owned this for about 10 yrs and just getting it on the road. Came with no rear bumper and appeared to have had a heavy duty hitch welded to the frame that was removed, had a brake switch mounted under the steering column.
Seems engine revs quite high at cruising speed of 60 mph, just sucks up gas like crazy.
How can I determine what rear end ratio is in it ?
Whats available in ratios. ?
How big of a job is it to change to a different ratio, ? I had someone do the brakes a little while ago and I believe they had to pull the rear axles out, rears are drums, front disc
No doubt will have further questions

[Sicklajoie]

If your rear end cover looks like this then you have an Eaton rear. Ratios are 4.10s and 4.56s. I think they make custom gear sets for them but not positive.

[mike16]

usually its one of only two rear end types.

if you have leaf spring rear suspension its probably a dana 60 rear.

if it has a coil spring rear suspension its probably an HO 57 rear

the ratio most likely is 4.56 which explains the hi fuel consumption and hi reving.

if its a dana rear you may be able to get a different set of gears that are more fuel and hiway friendly

if its the HO rear your stuck with those characteristics. it is correct that they come with a 4.10 or 4.56 ratio and several years ago a custom 3.90 ratio was made available thru the aftermarket. but for the expense it would not have changed much

search this forum to see what each rear looks like to more certainly identify it.

I dont know if a coil dana rear was available but if so its worth the search and you then can install a wide veriety of hiway friendly gears

[Jeff's bowtie's]

Eaton Ho 52

[Mike C]

All the Longhorn trucks were leaf spring. The '70 I have has a Dana 60 in it. It was a GMC small block 4 speed FWIW.

[Shaky]

Originally Posted by Sicklajoie

I think they make custom gear sets for them but not positive.

I've heard stories about a short run of 3.90 gears for these years ago, but they are like unicorns and I've never seen any in the wild. It seems like there's enough demand that somebody could make money off another run (are you listening Yukon Gear?).

[Bigdav160]

Since you have an automatic transmission it would likely be beneficial to look into a more modern overdrive transmission. A 700R4/4L60 would work well as would a built up 200-4R

[Already Gone]

Here are the Power Train Specs for the 72 model. Unless there is an optional rear end ratio listed on the spid compare this chart to your trucks power train.