They are 35 pin "Ampseal" connectors.
http://www.digikey.com/catalog/en/partgroup/ampseal-series/27450http://www.digikey.com/product-detail/en/776164-5/A105102-ND/2327367They're pretty neat; they are sealed on the backside with a solid silicone barrier and the pins crimped onto the wires puncture holes in them so they automatically seal as they are installed. There is no need for a seal crimped onto the wire nor a plug like on other weatherpack connectors. They do make plugs to seal holes in the backside if one is depinned or punctured on mistake.
The male connector body has a silicone seal and the connector header also has a perimeter seal to seal off whatever you bolt it to. The lock tab is quite sturdy and there is no chance of these ever coming undone on accident between that and the silicone seals.
Ironically the sealed MS Pro and Microsquirt units now ship with these connectors and they can be submerged. I was using them before they were cool! I bought mine online from Digikey. They are very inexpensive, less than $10 each per side and a bag of 200 pins was like $8. They are color coded and keyed differently, so there is no chance of plugging them into the wrong headers. I bought black (chassis), blue (MS2), and grey (eventually for the MSX if I upgraded).
http://www.google.com/imgres?imgurl=http...=88&ndsp=26http://www.google.com/imgres?imgurl=http...t=0&ndsp=18http://www.google.com/imgres?imgurl=http...t=0&ndsp=18Assembly is straighforward; crimp the pin to the wire and put the connector in the "service" position. The red lock on the front side is basically slide forward slightly but not removed. You then insert the pins through the back seal. When they are all installed properly the red lock is pushed back into place and the pins can no longer come out.
To remove a pin, the lock is moved and you simply twist the wire slightly to get it to pull out.
The OE crimpers are crazy expensive, but I was able to make do with generic weather pack crimpers and I also soldered them to make sure they never come loose.
I soldered and heat shrunk the wires to the header on the interior side of the firewall. Pro tip: Crimp pins onto the wire on this side and they will slide snugly onto the header pins making it MUCH easier to solder. Use large heat shrink or a zip tie to provide some strain relief, and anchor the harness bundle with a little bit of slack within 6" of the header with a P clamp or similar.
DigiKey has a pretty detailed catalog and PDF's you can download for everything you want to know about these.
