68 GT 500 Transmission

[Steve Z]

   I am looking to purchase a 68 GT500 that does not have the original Transmission. My question is 1. Do I worry that that will affect the overall Value of the car? 2. What should I be looking for as a replacement that would be as close to the factory as possible? Date codes, Vin numbers etc. The car currently has a 4 speed top loader from a Galaxie 500 that I have been told. Thanks Steve

[PR]

I don't think a galaxies trans will work, too long,

[Bob Gaines]

   I am looking to purchase a 68 GT500 that does not have the original Transmission. My question is 1. Do I worry that that will affect the overall Value of the car? 2. What should I be looking for as a replacement that would be as close to the factory as possible? Date codes, Vin numbers etc. The car currently has a 4 speed top loader from a Galaxie 500 that I have been told. Thanks Steve

If it is a GT500 and not a GT500 KR your chances and expenses will be better. The KR CJ trans is specific to Cobra jet cars . The R servo only fits a CJ C6 case. The CJ trans comes with a cast iron tail shaft while the GT500 has a cast aluminum one.  The GT500 H servo will fit in a generic C6 case found in all 67-70 Mustang and full size car. You have to be careful however because a case from a column shift car regardless of if KR or GT500 will not work in a floor shift car without a shifter lever change on the transmissions. That is about a 130-150.00 repro part. There is a date code clock on the main case but typically hard to read because of casting slag wear etc. There is a ID metal tag that is secured to one of the modulator bolts. They are typically VIN stamped on the top side in one of a couple typical locations that can't be seen once installed.

[Bob Gaines]

I don't think a galaxies trans will work, too long,

The galaxy trans has two shifter bolt patterns so the shifter will fit the correct Mustang tunnel hole but since the tail is longer requires a shortened driveshaft . It will work but not without modifications.

[Coralsnake]

Unless you have a very very original Shelby, its probably not going to effect the price significantly. Each transmission was specifically stamped with a VIN for the specific car. Many cars do not have their original drivetrain components. I would say its pretty much baked into the price of most cars already. Regardless, its less than 5% worse case scenario.

[pbf777]

The R servo only fits a CJ C6 case.

     Perhaps in 1968 (?), but further forward in time, many (perhaps even most) of the cases not originally equipped with the "R" servo however were machined to accept such.   

     Scott.

[Bob Gaines]

The R servo only fits a CJ C6 case.

     Perhaps in 1968 (?), but further forward in time, many (perhaps even most) of the cases not originally equipped with the "R" servo however were machined to accept such.   

     Scott.

Scott, I concur that there are equivalent servos made in the aftermarket that perform nearly the same however they don't look the same on the outside. Modifications can be done to cases to make things fit that otherwise would not. The OP was concerned about correct parts "as close to factory as possible". So my response was in context to factory parts that look correct without modification.     

[pbf777]

     Just to clarify, I was solely referring to the C6 main cases as being machined by Ford to accept the original Ford "R" servo, even though in the production assembly they may have received other. I would say that Ford chose to adopt the manufacturing requirement change (post 1968+/-) to reduce confusion/complications in production or as parts replacement.     

     Scott.

[Bob Gaines]

     Just to clarify, I was solely referring to the C6 main cases as being machined by Ford to accept the original Ford "R" servo, even though in the production assembly they may have received other. I would say that Ford chose to adopt the manufacturing requirement change (post 1968+/-) to reduce confusion/complications in production or as parts replacement.     

     Scott.

I am not aware that a original R servo will fit in anything but a original R servo case without additional modification. Regardless original Ford R servo are seldom if ever found separate.

[68blk500c]

Back to the original topic, which is a 68 GT500 C6:
 
All of these are identified by PGB-W tag code, if it is still happens to be attached to the servo (H servo).  The correct main case has different casting characteristics which allow it to fit properly in the F body.  An A body, or truck C6 is not the same main case.  Those may mount to the chassis, but there are other clearance issues without modifications.

[Bob Gaines]

Back to the original topic, which is a 68 GT500 C6:
 
All of these are identified by PGB-W tag code, if it is still happens to be attached to the servo (H servo).  The correct main case has different casting characteristics which allow it to fit properly in the F body.  An A body, or truck C6 is not the same main case.  Those may mount to the chassis, but there are other clearance issues without modifications.

Not that it makes a whole lot of difference now but actually the OP was not aware of the differences between a GT500 and a GT500 KR because his question referred to a GT500 KR that he had just acquired which he indicated to me in a PM. He is a Boss enthusiast that doesn't know a lot of the differences in 65-70 Shelby's but does know that he likes them. He realizes now that those two extra letters (KR) can make a big difference when discussing components.

[Bigfoot]

It's hard to see the VIN on a trans for 99% of the enthusiasts out there.
Especially when installed......
If u find a tranny which is correct but from different Shelby (etc) I wouldn't sweat it.

[gt350hr]

  Bob and Scott,
      Years ago , I made a simple aluminum disc as a go - no go  device for checking servo bores on C6 cases. Very simple , very fast and accurate. "Most" of the '68 and later cases are large enough to accept the original "R" servo assembly. "Early" cases almost always need to be enlarged and it is a touchy process. From a "builders point" , the C6 is a little different animal in that the servo activates an "apply lever" that is available in different ratios (similar to an engine's rocker arm). This allows custom tailoring of the shift timing and harshness. In racing applications shift timing is critical on this transmission in terms of ET and clutch/band life. We often remover the R servo and used a D with a different apply lever. Originality went out the window obviously.
    Aftermarket servos use a vastly improved lip seal for superior sealing. No way would they pass a concours though.
  Randy