Auto Trans Swap on a 1960 MK2 3.8L

Hi, just had a service done on my MK2 DG250 Auto Trans before Easter & mechanic advised of a dripping leak from the front seal of the torque converter. This box has been giving me issues with leaks, shuddering at low speed especially on take offs & on slight inclines!
Given the trans has to come out to rectify the oil leak, & parts are becoming scarce plus the costs for rebuilds I’m re-searching this option,

A local contact has for offer a well-known history on a good 1984 Series 3 Jaguar 3 speed BW66 auto with Bell housing, Flywheel, torque convertor. & starter motor.
I understand the bell housing bolt pattern is the same & the rear drive shaft(s) could revert to a one-piece unit with this changeover & that would be a bonus.

Before I jump into this, has anyone on this forum done this changeover before who can advise re any issues encountered such as :-
1)Removal of DG box without removing engine (lower engine a tad at the back to get to the top bolts?)
2)Bolt-up of the BW66
3)Installing a transmission cooler, (assuming it does need a cooler?) the routing of new oil pipes & location of the cooler as the space behind the grill is now occupied with a thermo booster fan.
4)Location of dip-stick
5)Connection of gear selector linkages back to the original steering wheel gear selector lever
etc, etc

I reckon I could do this myself at home but it’s getting the car up to a reasonable safe height to drop the DG out & refit the BW66 is the issue. Don’t really want to pull the engine & gearbox out the top as one lump, I did this 25 years ago & that was scary by yourself!

Any comments or lessons learned would be appreciated.


A BW66 will give you more revs, as there is no direct drive clutch and there is always slip.
Another diff ratio will solve that.
You also need the flex plate of the BW66, to bolt on the torque converter.
Also you need a new prop shaft ( or modify the existing one ).
Indeed it needs a cooler.
A new gear selector plate that will have the right indentations, and indication plate ( order is different )

I went for the Johns cars kit and used a T700-R4 GM box ( 4e speed with direct drive and overdrive )

Thanks RushP, that helps a lot.
So, the gear selector plate is at the gearbox end & the indication plate is the one at the steering column end with the selector, yes?

Hi Pierre , I did. thuis conversion at my 3.8 mk2 1964 last year . ( and it isn, t finisheshed yet …)
It is done by quite some people. You should use the complete set of the Xj , also including flex plate and starter motor .Installing the box is rather straight forward. Not easy but good to do without removing the engine. The challenge is the routing of the shifter cable , use the 250 one , mount the shifting rod 180 degrees turned at the box side . Change of the cam at the column inside is the second challenge , but not heavy. Important is the kick down cable of the S3 box , I mounted it under the carbs at the steel strip but not satisfied. Haven,theta another solution.Didn’t mount a cooler as the box doesn’t,t need to work so hard .
My disappointment was / is that the box doesn’t,t shift from 2 to 3 , think nothing to do with the swap but with the box itself.
Regards Roger


Thank you Roger for your input as well, that’s a bit of a worry if your gearbox doesn’t shift from 2nd to 3rd, do you have to pull the box again?
I will be using the complete set from the XJ.
Appreciate your photos of the steering column end, understand the issue here now
Can you identify the shifting rod item that you refer to being mounted at 180deg from this parts listing for me please.


I replaced the PNDLR plate with a PRND21 plate ( from a 420 ) at the steering column.

Thanks Peter

I just need to know which shifting rod item has to be re-mounted at 180deg as per Roger’s response

If you’re going through the trouble to install a new transmission why not install a 700r4? You’ll get a lock up torque converter and overdrive and a more modern transmission with better parts availability. Im in the process of doing that to my 1961 mk2. All i have left to do is order the adapter from John’s Cars

I wouldn’t wait too long…

Hi Rome55 & RuschP.
Roger/Peter, What BW66 Rear Transmission Mount did you fellows use? Did you use one from a Series 3 XJ6?

Hi Pierre, yes i used the S3 spring .
I also reconstructed the wat in wich the Kick down cable is actuated. It has now the Full +/-50 mm stroke

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Roger, OK you used the S3 Spring, but what rear mount did you use, Like this one pictured?


The 700R4 is a very tight fit with other possible issues…

The shuddering when pulling away and at low speeds is probably the propshaft not being aligned correctly, there is a specific procedure to do this (left and right as well as up and down) and if its wrong its very noticable.

Yes, I’m aware of the prop shaft(s) alignment procedure Andrew, but the DG250 has to come out anyway to replace front seal & others that are leaking like a sieve!!
I’ve decided to replace it & got the BW66 at a good price & committed now with sundry other parts on hand & in transit to make it work. :slightly_smiling_face:
The rebuild on a DG box is anywhere between $A6-8K

I’ve now got all my components together & just waiting for my mechanic to allocate a slot for me in his busy schedule, hoping for next week.

The only thing left to do is to sort out the speedo cable.

I assume the speedo end of the cable will remain as is but the BW66 speedo drive end of the cable will need to be reworked to suit that drive.
Length of the cable will also need to be checked as well once the vehicle it’s up on the hoist & the BW66 is fitted up.
Again, assume there are instrument shops that can do that work.

Any comments/suggestions appreciated on this point

Forgot to add, I’ve purchased a new reduction starter motor to suit the XJ6 flywheel.

DG250 auto now removed & the BW66 Transmission & starter motor now fitted to the MK2.
Tailshaft is at the m/c shop for shortening of the front section. The front yoke & UV joint pretty worn & will need to be replaced.
Oil Cooler about to be mounted behind front bumper.

Q;-Does anyone know if a XJ6 S2 BW66 speedo cable is compatible with the back of a MK2 speedo?
I have the correct right angled drive fitted to the transmission