5speed Transmission Rubber Mount
S30 does not fit - different bolt pattern from rubber mount to frame bracket (1 hole vs 2)
(I guess if you HAD to, you could re-drill to correct bolt pattern...)
510 does not fit
But, S13 / S14 / & most likely the 90s Nissan pickup (with the KA engine) fits!
Here's how we figured this out:
Tim (wookieballa) suggested the idea, so I reached out to Eric @ JDML, Jan (yawnnycash), Dave (sennavsprost), & Mark.
Eric @ JDML happened to have a customer 510 at the shop that has an SR20 swap. He sent me pics and dims of the tranny mount that was on that car - it turned out to be a S13/S14 unit, and all bolt hole dimensions checked out.
Tonight, I went by Mark's place to see his assortment of S14 parts including both stock S13/S14 tranny mount and Nismo tranny mount. The pics below are of my busted C10 tranny mount (on the left) and the optional Nismo tranny mount for S13/S14
My C10 trans frame bracket bolts up 100% fine
The S14 rubber mount bolts up 100% fine to my Z/ZX 5spd trannies
The only difference is that the stock S13 / S14 mount is about 1/2" - 5/8" thicker than C10 rubber mount
The optional Nismo S13 / S14 mount is more like 3/4" thicker than the C10 rubber mount
That means the tail of your tranny will sit that much higher in your trans tunnel
Your engine + trans will in effect be pitched forward longitudinally a hair more than with the C10 stock mount
Not enough to cause any serious drama to your drive shaft u joints
The only place where you might have a slight interference is the top of the tranny where the shifter plugs in and how close that might be to the top of your trans tunnel.
Mark gave me his stock used S13 / S14 trans mount to mess around with.
When the 5speed goes back onto the Skyline on Saturday I'll try it & report back - looks awfully promising! I think it'll work fine...
Thanks to all involved in figuring this out!