dre

Can anyone tell me what rear end gears come stock on a 72 442 350 4barrel? I will be putting in a high compression 455, big boy cam, w/TH400(w/a stall of course). I know I have stock gears at this point because nothing was changed out. What rear end gears will I need with this application?

InfoJunkie

ID code is located on the right hand axle on the back side about 3" from the center section.If you can still see them through the rust
Standard Diff
SA=2.73, SC=3.08, SR=3.23
Limited Slip Diff
SB=2.73, SD=3.08, SS=3.23 TM=3.42, TO=3.73

dre

I wasn't able to see completely through the rust. I found some numbers on the axle that was on the drivers side that read 67890. Not sure what this means. However, it is 10 bolts. What could this mean?

jensenracing77

on 72 you will find the numbers on the front side of the passenger side axle tube. there should be a (i think it is) 6 digit number. the first two will be the code for the gears. that is if the gears have never ben changed. and also if the rear end has never ben changed. the last 3 or 4 digits are a date code.

dre

i saw "CCA030B1" what is this?

jensenracing77

i think that will be a 2.73 anti spin

dre

Yes. I'll try to read it again just to make sure I didn't misread it.

dre

What does that do for me being that I will be putting in the 455 hi compression engine w/a th400 tranny? Will I need to change out my gears?

jensenracing77

just a mater of what you want to do with it. first you will want to confirm that is what you have for gears. you may need to change the rear end oil anyway so pull the cover and get the numbers off the gears. if that is what you have, you could built the engine for the gears or change the gears. that should be an 8.5 rear end so there will be several different gears available for it. you may be able to have an ok gas mileage with great power with the 2.73. i think someone else should answer this that know more about it. i think a proper compression, cam, and intake selection could work ok with these gears but it is a matter of what you want to do.

Rickman48

2:73 gears are great on the highway, but tire smokers on the street w/any kind of power!
3:73's are just the opposite - great acceleration, but a gas hog on the highway.
IMO, since you're changing the trans, too, I'd go with a 700r4.
More expense, [adapter, switch, driveshaft and wireing] but it'd have decent acceration in 1st, and the torque of a 455 would overcome the RPM drop to 2nd.
On the highway, you'd be a little over idle @ 55 MPH!
Six of one - half dozen of another, kind of a toss-up!
Unless you found a decently priced drum-to-drum setup, the new parts and labor prices would be pretty close!

dre

This will be a street car that I'll bring out on sunny days or special ocaisions. However, the application i'm working towards will have a CR of 10-10.5:1, street/bracket Lunati cam, w/full roller rockers w/ big valve C heads. I have a rebuilt TH400 that costs me nothing.(free from a family member), so I don't want to spend the extra money on a tranny if its not needed. I'm not too worried about gas mileage.

firefrost gold

should work just fine with your car do you like how it runs around town now? I have 2:56 in my driver is as stated great on the freeway will pull just fine off line but want to got to a 3:08 set up for more go at the light and still be a good all around car.
A small stall in the 2000 range to 2500 will help get it going better too . Nice thing about leaving it is the speedo is the same and you can judge the improvment of the new 455 better .Then hit it with some gears if its not all you wanted jmo

dre

Thank you for the suggestions everyone!

sx455raidercelticfan

if your going 2 drive it on the freeway id go with 308 or 323s youll have nice bottom end and mid/top end if its going 2 be a week end track car go with 373-456 but you wont be able 2 drive it on the freeway over 50mph, gears make a BIG difference, i think a street/strip 455 with 308s is nasty!!!! youll have major jump because of the 455s torque and mid/top end because of the 308s

Rickman48

With that type of usage, go for the 3:23's and about a 2500 convertor - great all-around combination with a free T-400!