Road Runner Nest

I just got my '71 GTX home and the guy I bought it from couldnt' tell me whether it had an 8 3/4 or Dana so he wasn't much help to say the least.

So I think I've done what homework I can and have hit a wall. Here's what I know so far:

The door jam decal says the car was built in Sept 1970

The block casting is correct at 253643-7 (1966 - 1972 440 RB)
Date stamped July 23, 1970 (cast on the 10pm night shift)

The pad on the top of the block says either a "C" or a "G 440 HP" (G = 1971, C = 1966) Also has symbols indicating a .010 undersize crank...for whatever reason.... /shrug

The casting date doesn't seem to match the pad stamped year which I find strange.

My problem arises at the VIN sequence stamp on the machined pad on the passenger side of the block above the oil pan. I can only make out 3 and a half of the digits. The area is clean but heavily painted orange. I tried paint thinner to remove the paint and of course nothing came off.

Is there a trick to getting the stamped numbers to show up better or a way to remove the paint? Or should I assume, since the other numbers and dates seem to correspond correctly, and the 3 numbers I can see are correct, that it is in fact numbers matching?

Also, does anyone know where the 727 transmission stamp should be? Apparently these were also stamped with the VIN sequence number.

Thank you for any help.

The 727 is stamped the same way as the engine, on the side of the case. I think there's a pad on the passenger's side, about 1/3rd the way up the side of the tranny case

i need pics of the block to help you

A32 Super Performance Axle package - 4.10 Dana (440 & 426 only)
A33 Trak Pak package - 3.54 ratio (440 & 426 w/ 4-speed std.)
A34 Super Track Pak package - 4.10 Dana (440 & 426 w/ 4speed opt.)

A36 Performance Axel package - 3.55 ratio (340 & 383 both, 440 & 426 auto.)

on the fender tag
The block casting is correct at 253643-7 (1966 - 1972 440 RB) ?

for 440 1971 RB IT IS 2536430

yes G is 1971

042 - 3.23 open, 8 3/4, 10" rear drum - front disc/LD drum
043 - 3.23 s/g, 8 3/4, 10" rear drum - front disc/LD drum
044 - 3.23 open, 8 3/4, 11" rear & front drums
045 - 3.23 s/g, 8 3/4, 11" rear & front drums
046 - 3.55 s/g, 8 3/4, 11" rear & front drums, (A36 Pkg)
047 - 3.55 s/g, 8 3/4, 10" rear drum - front disc, (A36 Pkg)
048 - 3.91 s/g, 8 3/4, 11" rear & front drums, (A31 Pkg)
049 - 3.91 s/g, 8 3/4, 10" rear drum - front disc, (A31 Pkg)
050 - 3.54 s/g, Dana 60, 11" rear & front drums, (A33 Pkg)
051 - 3.54 s/g, Dana 60, 10" rear drum - front disc, (A33 Pkg)
052 - 4.10 s/g, Dana 60, 10" rear drum - front disc, (A34 Pkg)

Lynch Road tags are set up a little different then the other assembly plants,

I typed my message while I was tired and wasnt clear.

Is there a way to bring out the stamped numbers that are coated in paint on the engine block by the oil pan? Paint thinner doesn't work, how bout brake fluid??

Does it make sense that on the engine block the casting date isJuly 23/1970 (the car was built Sept. 17/70) but the pad by the distributor has "G" stamped for '71? If thats the case I would assume that Chysler used a 14 month old block when they built the engine. Also it cant be numbers matching cause the engine was built after the car.

Thanks again for your help.

With a scheduled production date of September 1970, a block with a July 1970 casting date would be about right. 1 - 2 months lead time from the scheduled production date to the block casting tends to be what I've seen. Silly part is, I've never looked at the date on my SSP (an August 1970 build date), but I'll bet it's in the June / July timeframe as well. The "G" code on the ID pad isn't the casting year, it's the designation of the model year it was cast for - hence 1971.

As far as getting to the point of being able to read the stampings - I've found a wire wheel tends to get the paint out of the way nicely. But based on everything else (including the numbers you CAN read matching your car), I'd be pretty well convinced that's the numbers matching block. However, I'd still take the time to clean up the block enough to verify it.

Thanks Dave, I'm concerned a wire wheel will wear down the stamping, thats why i wanted to use a solvent of some kind.

Great site, I hope I will be able to contribute at some point instead of being a black hole of B-body knowledge.

I wouldn't worry about it - it's cast iron we are talking about here. If you are worried about using the wire wheel on it, don't use a steel one, use a brass one. Should take the paint off without any risk of damage the cast iron.

Glad you are here. Being a bit of a black hole is the only way to learn. Heck, that's how Eric, Bruce and myself came to have the knowledge we have about them!

Don't worry about the "Maltese Cross". Yes it does mean one or all of connecting rods or mains are undersize, but these crankshafts are extremely strong and durable. The exact mains and/or rod journals affected are stamped on the crank itself. It could be only one journal and may only be .001" not .010".

easy to tell if it's dana or 8.75....if it has a cover, dana if it looks like a ford 9" where there is no cover as you look at it from the rear of the car, it'd be a 8.75

wow, dam thats helpful. Definitely an 8 3/4 but with a 741 third member. I read it should be a 742 or 489. Hope its not going to blow on me

they made a 741? i've only heard of 742 and 489.

NOrrTH wrote:Thanks Dave, I'm concerned a wire wheel will wear down the stamping, thats why i wanted to use a solvent of some kind.

Great site, I hope I will be able to contribute at some point instead of being a black hole of B-body knowledge.

I wouldn't use any power deals,Id go to your local hardware store and get a set of different type of wire brushes,i say this because some are stiff and some are softer(different metal whiskers).When I was cleaning my 400 block i had a soft brush and a can of kerosene just dabbing with the kerosene and then wiping away with a rag.I also kept a can of gunk remover.It was a whole combination of awesomeness because that block is very clean now.ha ha ha

I think if we didnt have questions this place wouldn't be what it is.We would all be bored.

to get the cast numbers
you can take a graphite rubbbing of the block using newsprint and a graphite stick
as long as the cast numbers are raised. to high light the stamped ones use white chalk and use a black light
you can get one at any pet smart used for finding pee.
and wipe away the excess this way you dont remove any paint. and have to repaint the block.
also a good way to tell the rear end if it is original there should be a metal tag on one of the carrier bolts
showing the ratio.

741 case
Differential 57-early 69: 25590/25520
Differential Late 69-74: LM104949/LM104912
Pinion inner: HM89446/HM89410
Pinion outer:M88048/M88010
Seal: 8515N

742 case
Differential : 25590/25520
Pinion inner: HM803149/HM803110
Pinion outer: HM89443/HM89410
Seal: 7216

489 case
Differential: LM104949/LM104912
Pinion inner: M804049/M804010
Pinion outer: M88048/M88010
Seal: 5126