Original 8 3/4 Center Section ?

[Hard_ChargerR/T]

Hello everyone,
The other day I was looking under my car ('69 Charger RT/SE) to see which of the center sections that I have. I had looked before but I didn't realize that there were two cases that were one digit off. Anyway, this time I looked and saw that the case was a 741 and not a 742 which I had assumed. I was under the assumption that this car was pretty much stock #'s matching. So, my question is this, would the factory have put this smaller case in a heavy car like this with a 440 magnum motor? I thought the 741 case was reserved for smaller/low hp applications. I am thinking that this is the result of an after the fact swap. Anyway, if anybody knows anything about this I would be glad to find out. Thanks a bunch.

Matt

P.S. Is there anyway to find out stamped on the car what the casting number of the original centersection was?

[jelsr]

The chassis and oval track books refer to the 742 and 489 as performance type rears. The others are the grocery getter type and are not recommended for performance applications. Neither of the aforementioned books get any more specific than that. Likely was swapped in by someone that wasn't aware of the difference. Can't say on the codes, maybe some of the other members can help on that.

[Hard_ChargerR/T]

That's what I was afraid of. That is a bummer, finding a good center section is so darn expensive now. Well, if anyone knows how to figure out what it was originally equipped with, I am still interested. Thanks again.

Matt

[jelsr]

Too bad you're so far from here, we have lots of them here in flatland USA. Virtually everything had the 8-3/4 from the late '50's to the mid '70's, cars and P/U's. All are interchangeable, but the innards are not. Several companies are selling gears now at reasonable prices.

[John Kunkel]

Although the 741 wasn't original in your car, don't sweat it unless you're concerned with originality. You'll have to make a ton of power before you'll wound the 741. They've been known to run in the nines without breaking.

[ChargerMD]

A 742 case should have came in your car. All the cases I have ever pulled behind a big block have been the 742 or 489 (later models) cases- even in the c- bodies. I have not had much luck with the 741 cases- have always seemed to leak at the front seal (could be just because the ones I've had are worn out). I'm assuming yours is an open diff (never have seen a factory closed 741 diff) so the good news is that you can find a open 742 diff in a c-body or a early 70's truck fairly easy.

[Blaine Peterson]

A '69 R/T would have come with the 489 case, unless it was a four speed car, then it would have come with a Dana 60 rearend, if memory serves me correctly.

I think the 742 case was pre-1968.

[dkn1997]

if you really want a 742, pick up an open one, probably won't be more than 50-100 bucks. If your 741 is a suregrip, you can use just the suregrip unit to make an open 742 into a suregrip or buy a new unit. you will need the correct ring and pinion (741 & 742 gears will not interchange)

check out:

www.autohobbydigest.com

click on tech articles, and scroll down to the mopar 8 3/4 rear end guide, tons of info there on interchangability.

if you plan on getting an entire used centersection, stay away from ebay. Those guys are out of there minds. You will not see a decent used one under 400 bucks, and they might be junk, no way of knowing, plus cost a fortune to ship.

[Hittman55]

HP rear end units types and rear:

1968 and earlier used 489 Clutch pack, Dana Manf
1969-73 742 cone and cup, Borg and Warner Manf

[dkn1997]

489 is the cone type ('69 & up)

742 is clutch type ('68 & earlier)

[Hittman55]

Your right thanks dk1997 had the case numbers A$$backwords