any 3.08 fans?

[Hoffman65burb]

Hey,

Ive found a 12 bolt posi with 3.08 gears out of a 1970 leaf spring truck, Any flaws/advantages to these rear ends? is it a higher gear ratio than my stock non-posi 12 bolt rear end in 69? Will it pick up pretty good with a 350/turbo350 with 15x10s (havent chosen what size tires to use yet)?

[N2TRUX]

It depends on tire height and HP/TQ numbers. It's not the best for an under powered motor, and sucks if you run tall tires. On the other hand it's a good overall gear for mileage.

Personally I think a 3.42 is better, and 3.73's rock if you don't care about mileage.

[Longhorn Man]

if freeway flying is more important than launching at the stoplight, then a 3.07 is awesome. I cruise at 80 all the time and do it without stressin my engine.

[Hoffman65burb]

I could always change JUST the gearing right? im not very familiar with differentials so ill have to do some reasearch. Is the posi a seperate component from the gearing? Also would 3.08's pick up pretty decent? The motor is just a 87 tbi motor converted to carb, holley 600, hei, wires, full length headers duel exhaust is it still pretty underpowered for this rear end?

[Green Machine]

Good gears if you don't have an over drive. Our 68 with 307 and 3 speed is geared that way stock and works good with a 28" rear tires. Cruises around 2200 rpm @ 60. The other common option was the 3.73, better around town but much more busy on the highway.

[Longhorn Man]

your 69 obviously has no optional gear since you don't know what it is (not listed on the SPID)
Whats the original engine and tranny combo?

[Hoffman65burb]

it was a v8, the 350 i pulled out of a 69 block so that could have been the original motor, it also had a 3 on the tree

[BCOWANWHEELS]

350 &350th, 3.07 gears are perfect

[Longhorn Man]

you should have a 3.73 in there assuming the rear is original and not messed with

[lilred67]

i have them in both of my trucks. one w/ 4speed and the other w/ turbo 400.i like them except when i'm really loaded i.e. 4000lbs +. but no more than i carry that much weight they are great.....

[capev86]

unless i lived in flat country, spent all my time on the highway and never towed a trailer, 3.08 gears would be "ok". we swapped my dad's ex-texas 87 burb out from a 3.08 to 3.73 using the rear axle from his 84 and it woke that lazy truck up but with OD it's still pretty smooth on the highway. you just multiply numbers > (3.73x.7=2.61, 3.08x.7=2.16). some form of overdrive trans is a much better way to go in that it gets you the best of both worlds

as for hoffman65burb.....you converted a tbi to carb. i'm looking to do the opposite on my 72 burb 3/4 ton 2wd. i am ditching the original 307 in favor of a 406sbc. eventually want to swap adapt it to tbi for better mpg and more efficient power. gonna stick a 454tbi unit on a hogged out small block tbi manifold to get good flow. tbi is supposedly better at the low end than tuned port and the bigger tbi will flow well enough to allow that 406 to breathe like the 750q-jet it sports now. i just like the idea of having my fuel delivery system determined by precise computer control, rather than rely on a vacuum operated funnel just dumping fuel in there. and the nice thing is that tbi's use air boxes much like carb engines do, so it will look very stock to the casual glance w/ a big factory air box on there!

[19673ontree]

I put a set of 3.08 gear's in my 67 a few weeks ago , it is the best thing I have done to the truck so far , I drive it a couple hours trip to TN. once a month sometimes twice a month and to run 60 it sounded like the hood was gonna blow off and got 2 miles per gallon you could watch the gas hand go down
with the 250 six cylinder and the three speed on the column I can run on the interstate at 80mph it is perfect !
around town I use second gear more now but with it all added up the 3.08 gear is the best all around ,,mine had a 3.73 which I will keep out here in a bucket of oil but it will probably never be reinstalled

[BCOWANWHEELS]

WITH A SIX ( 250 ) and 3.08 gears i'd recomend a sm465, 4speed if you ever want to haul or pull a trailer because the 3.08 and a 3 speed manuel trans pulling out will be a bugger loaded. it is tough sometimes even with my 3.73's like on a hill etc. jmo

[Tx Firefighter]

They are all I care to run in my trucks. Around here it's all highway miles to get to anyplace. It's either run an overdrive and 3.73s or a cheap TH350 and 3.08 gears. Cheap wins every time in my world.