Think I´m in trouble

Long story short; Engine in my -74 S3/88 was shot. Found a 2.8 Daihatsu Rocker, which already sat in an S3 - an 109. In my in infinite wisdom, I was "hm, probably same gearbox, easy swap". No.
My 88 got a 12 bolt pattern gearbox. The adapter ring has a 10 bolt pattern, and I´m an *****.

Questions
Anyone know if there are adapters to fit this 12 bolt gearbox?
If so, where can I find one?
Will a gearbox from a 109 fit the 88?

//Car1

109 and 88 box's the same. Is it a case of just having to miss out two holes ?

Hm, I just got these, taken of the donor 109. Compared to my above, they seem to be quite alike, and the #nr seems to be the same. 11 holes in this one though.

The donor/from the 109


Mine/the 88

One stud cannot be used due to starter being on opposite side , and one omitted on adapter on opposite side but cannot tell why.
Rest look like they will fit fine though clearance for slave clutch cylinder looks tight.

#nr on my gearbox is 576714. Seems to be correct for S3, 4 cyl. Nr on donor gearbox is 576762, correct for a S3 2.6 l engine. What's the difference between these boxes?
//Car1

Bell housings on gearbox are different I believe so you need the donor one.

Thanks guys.
Are the bell houses between these boxes interchangeable? I´m guessing the 6 cyl box is the stronger one, so that option might be to prefer? I´ve been reading a few posts regarding broken gearboxes.
//Car1

Got a mail from MD Engineering/Cambridge, seems to be great guys. They suggest i use a box from a 6-cyl - will that fit? They also offer to have a adapter ring machined to fit the 88/4-cyl box. I´ll wait for your opinions to my questions above.
Thank you//Car1

One for jamesmartin I recon.

tottot said:

109 and 88 box's the same. Is it a case of just having to miss out two holes ?

Click to expand...

Thanks Tottot I´ve heard the boxes are the same, but also know the bell houses/bolt patterns differs. Best plan right now maybe to find a bell house - or a complete gear box - from a 6-cyl and try the fit on the 4-cyl.
//Car1

Pretty sure all series 3 gear box's are the same just the bellhousing differs.

Now got confirmation that bell houses are interchangeable. So, with the gearbox/es still in the car/s, what should I be aware of when attempting the swap?
//Car1

Oil will come out and there is a gasket between bell housing and box. You will be disturbing the front bearings for the input shaft and lay shaft and needle roller bearing on the main shaft.

Yes. Confirms what I´ve been able to find. No quick fixes here it seems.
//Car1

Check the box suffixes later series 3 suffix D primary pinion is not compatibkle with earlier ones.
Suffix D box should have the bolts for te reverse gate on selector in horizontalplane where earlier versions are vertical pair.

I can take pics of the 6 cylinder box and belhousing but I always thought thet the box was the same throughout and it is just the adaptor that is different?
Mine are all out the vehicle at the moment so easy to take pics to compare.

Blackburn said:

Check the box suffixes later series 3 suffix D primary pinion is not compatibkle with earlier ones.
Suffix D box should have the bolts for te reverse gate on selector in horizontalplane where earlier versions are vertical pair.

Click to expand...

Thank you. Suffix on this box is CA, hope we're ok.
//Car1

BruceB said:

I can take pics of the 6 cylinder box and belhousing but I always thought thet the box was the same throughout and it is just the adaptor that is different?
Mine are all out the vehicle at the moment so easy to take pics to compare.

Click to expand...

I think you're right. Earlier I just assumed the 6-cyl gearbox to be more robust, but now I'm pretty sure they are identical.
Thank you//Car1

I am pretty sure the six pot box is the same basic box as the 4 pot. The alloy adaptor is definitely different, not sure about the input shaft but a shufti at the parts book should sort that out.