Identifying my 904

[Professor Fate]

I've got a 904 family transmission I'll need to order parts for, but I'm trying to clarify what I've got first.
PK number is 4028815.

Stamping on the bellhousing pad is mostly illegible, but not a biggie.

So far, so good.
The trans. list on MyMopar lists this solely as a '78 360 application.

Also good, as this is destined to go behind an LA360.
Now it gets confusing. Most every source I've found says '78s were mostly lockup trannies (first year), but this one is definitely not- there's no machined input shaft tip for a lockup convertor.

So, I'm guessing the 360s got a heavier duty trans. than a standard 904, and was non-lockup. But, I can't find any reference as to whether this may be a 998 (four clutch, four gear planetaries) or a 999 non-lockup (five clutch, five gear planetaries). This is a transmission I bought in a lot, so there is no fender tag or option code to go by.
And just to further confuse things, it has (appears original, but no guarantees after 35 years) a non-weighted (I assume 318) convertor, which should not be in a 360-only transmission...

I know, I know- the best way to tell anything is to tear it down and see what I've got, but I'm heading out of town for a bit and don't have the available workspace to rip it apart at the moment... and would like to order the parts and have them on hand when I get back.
So, now that I've made a short story REALLY long; my questions are:
Does anybody have a reasonable assumption of what I've specifically got?
Does anybody have a link to a reputable site that gives more specific identification of the transmissions by PK number (or other means)-ie 998, 999, 32RH...? I had a good link, but it has gone dead.

 

[Dana67Dart]

It may have been converted to non lock up?

 

[Professor Fate]

It may have been converted to non lock up?

Doubtful... it was sitting in the guy's garage for 20+ years, said he thought he pulled it out of a Dippy, but wasn't positive. The cut off stub of a plastic speedo drive/cable would seem to confirm the lineage. Anything's possible, but the amount of caked-on grease and crud that I had to blast off of it makes me think it wasn't ever cracked open.

 

[Killer6]

If it's behind a 360 factory, it is an A-999, and yes it was a LU trans. Input spline count?

 

[413]

Could have been rebuilt 30 years ago and greased up again. They only way to know what's inside there is to open it up.

 

[Killer6]

Doubtful... it was sitting in the guy's garage for 20+ years, said he thought he pulled it out of a Dippy, but wasn't positive. The cut off stub of a plastic speedo drive/cable would seem to confirm the lineage. Anything's possible, but the amount of caked-on grease and crud that I had to blast off of it makes me think it wasn't ever cracked open.

They did make a 4028878 non-lock up A-999 the same year, I remember the early '80's & how many folks despised those L/U trannys, it wouldn't surprise Me one bit if that thing was converted 35-40yrs ago. Back then there were a lot of good local trans guys, certainly capable of making the swap happen, I'd say if so You're already 5 steps ahead......

 

[transman]

My catalog lists a single wire lockup solenoid for a 1987 transmission. As Killer6 says, count the spline teeth on the input shaft.

 

[Professor Fate]

If it's behind a 360 factory, it is an A-999, and yes it was a LU trans. Input spline count?

Non-lockup input shaft, as shown above. Lockups have a machined nose in addition to the different spline count.

One thing I forgot to mention, the case has the smaller cooler line ports for 5/16 cooler lines, not the bigger ports for 3/8 line that lockups used. Doubt that anyone would have gone to the trouble of REDUCING the cooler line size...

 

[Professor Fate]

They did make a 4028878 non-lock up A-999 the same year, I remember the early '80's & how many folks despised those L/U trannys, it wouldn't surprise Me one bit if that thing was converted 35-40yrs ago. Back then there were a lot of good local trans guys, certainly capable of making the swap happen, I'd say if so You're already 5 steps ahead......

They also made A998s and standard duty 904s in the same year, as well as factory non-lockup A999s. Which is why I need some clarification on the particular trans ID if possible.

My catalog lists a single wire lockup solenoid for a 1987 transmission. As Killer6 says, count the spline teeth on the input shaft.

No lockup wire plug on this transmission, just the standard 3 prong NSS (I do have a legitimate LU A999/32RH to compare it to). Many of the (non-truck) lockups were fully hydraulic and had no lockout connection (most cars would not require a tow/haul switch).

 

[Professor Fate]

My catalog lists a single wire lockup solenoid for a 1987 transmission. As Killer6 says, count the spline teeth on the input shaft.

Plus that's an '87, mine's a '78.

 

[Killer6]

Non-lockup input shaft, as shown above. Lockups have a machined nose in addition to the different spline count.
View attachment 1716257917
One thing I forgot to mention, the case has the smaller cooler line ports for 5/16 cooler lines, not the bigger ports for 3/8 line that lockups used. Doubt that anyone would have gone to the trouble of REDUCING the cooler line size...

Well, Your source + all of Mine (3) call it out as a '78 A-999 L/U behind pass. car 360's. That's a loooong download of trans codes on the 'Dippy' forum, the DC/MP Chassis racing/reference manual, & @VOETOM 's excellent manual. If somebody had a 318 Dippy w/a failed non-L/U A-998, they may have came across the superior A-999 needing a rebuild, but didn't want the L/U. Hence the trans man swapped the needed parts including the fittings to match the lines in the car. I witnessed many wild things folks would consider far-fetched today, just for the daily ride, that is My best honest guess.

 

[townsend]

Looks like another Mopar mystery.
The 1978 Chrysler parts catalog shows 4028815 as a 904 with lockup. Build date is July 27 1977.

 

[Killer6]

Looks like another Mopar mystery.
The 1978 Chrysler parts catalog shows 4028815 as a 904 with lockup. Build date is July 27 1977.

How many forward clutch frictions does the parts manual show for that '904'...?

 

[Professor Fate]

Looks like I've got a mutant on my hands, and no way of telling anything until I crack it apart. Was hoping for an easy answer, I should know better!
Thanks to all for your input!

 

[townsend]

Here's some info regarding the terms 904, 998 and 999.
In the Chrysler parts catalog under group 21 automatic transmission parts only the 904 is listed.
To determine the number of disc used, you must have the PK number. In all the Mopar performance books the 998 and 999 are covered but not in group 21 in the parts catalog.
Any comments or corrections are welcome.
By the way, the 4028815 shows 5 clutch disc.

 

[Killer6]

Here's some info regarding the terms 904, 998 and 999.
In the Chrysler parts catalog under group 21 automatic transmission parts only the 904 is listed.
To determine the number of disc used, you must have the PK number. In all the Mopar performance books the 998 and 999 are covered but not in group 21 in the parts catalog.
Any comments or corrections are welcome.
By the way, the 4028815 shows 5 clutch disc.

Yeah, that's kind of annoying the parts group lists the trans by the basic TF6/904 case style.

 

[transman]

How many forward clutch frictions does the parts manual show for that '904'...?

Many parts manuals will say (A.R.) which means as required.