[TR] J vs D Type Overdrives

[Barry Schwartz]

yes, not a problem, I have one on my 70 GT6.  The J type was used on the
three rail for a 1974 Spitfire so all you need is an adapter from that
year,  The problem is finding one.  It would appear that Victoria British
has one for about $170 which is a bit pricey but...  You could modify a
later adapter by cutting off the section of the adapter that encompasses
the single rail section so that it fits under the selector rail housing.  I
believe I have just such a modified adapter laying about somewhere (was
thinking of using it on my wife's, before I went with the later single
three rail tranny).  You can't use a single rail transmission on a GT6
however as the input shafts on GT6 and Spitfires are different lengths
(among other things).  I suppose you could make an adapter, but I don't
know if it would be worth it since ratios would be all wrong unless you
could get racing ratios etc...
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>As mentioned before, I am building a Spitfire bodied GT6, using a 73 GT6
chassis and running gear.
>
>I have 2 questions:
>
>1- The GT6 has a 3 rail trans that can be mated to a D type overdrive. I
was told the J- type overdrive is stronger and was used on 74 and later
Spitfires with the new, single rail, 'Marina' gearbox.
>I happen to have both transmissions and was curious if I could adapt a J
type overdrive to go on the 3 rail trans, or use the single rail on the
GT6. Any tips?
>
>2- I mentioned before I am also building the 2.0 liter inline 6 to be
'warmer', hoping for say 130 hp. Any recommendations on a cam and if I
would need head work, better con rods, induction or exhaust improvements? 
>
>Thanks for any wisdom you can impart. And also does anyone live near the
Ann Arbor area?
>
>Take care,
>
>Joao
>