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[rrblizard]

I'm thinking about adding OD to my '72 TR6 this winter. (don't want to waste the summer in the shop) Does anyone have any bright ideas where to find a unit? I missed out on an overdrive by $5 on eBay last week. Still kicking myself...

[TR3driver]

There are several companies that sell them reconditioned (but be sitting down when you see the price!):
http://www.quantumechanics.com/
http://www.overdrive-repairs.co.uk/
You could also try http://www.britisheuropean.com/ as they apparently bought out Waterloo Drivetrain (who used to sell reconditioned ODs).

Of course, another option is one of the 5-speed conversions:
http://www.blindmoosefab.com/hvda.htm
Not my cup of tea, but some people really like them.

A third option might be to convert to a J-type OD instead of A-type.  Although significantly more work (and IMO not as desirable), the J-type units are much more common and hence less expensive.

[rrblizard]

Thanks for the references. I see that Quantum Mechanics sells a modern 5-speed kit - at a price, of course. Type A ODs seem to be pretty hard to find these days.

I may just stick with the non-OD trans and stay off the highway...

[wadebbi]

I have overdrive installed by the previous owner.  How do I know if it's an "A" or "J" unit?

Thanks.

[TR3driver]

Probably easiest to jack the car up and look at the bottom of the unit.  An A-type will have a big (like 2-1/2") round brass plug as the lowest point.  The J-type won't have the round plug, instead it has a rectangular plate with ribs, held by 6 bolts.

Of course there are other types of Laycock overdrives out there; for example early Spitfires used a D-type and some MGB used LH-type.  But the TR6 only came with either A or J.