We ask a lot of our classic Camaros. After all, they were never designed support the parts we’re dying to transplant into them. Back in the ’60s, transmissions were small and, with only three or four gears, they didn’t need to be any bigger. Today, one of the most popular transmissions to transplant into early Camaros is the Tremec Magnum six-speed. The four “go” gears and two overdrives in the T56 Magnum offer the perfect blend of performance and highway manners. The big problem is that it’s far larger than what GM envisioned when they designed the Camaro’s transmission tunnel.
The simple solution is to do a little metal surgery and make the tunnel roomier. A task made simpler thanks to the transmission tunnel cap offered by Chris Alston’s Chassisworks. This preformed panel takes a ton of fabrication out of the equation and allows someone with basic tools and some welding skills to make their tunnel “Magnum friendly.” To preform the operation on our '68 Camaro project (Track Rat), we headed over to one of our favorite shops, Best of Show Coach Works in Escondido, California, to get Track Rat ready to receive its T56 Magnum.
01. To make sure we add enough room for the T56 Magnum in our '68 Camaro project, we installed it along with a composite LS engine we have at the shop. To support the transmission, we used the trans crossmember (PN 5916-F10-05, $256) that came with the Chris Alston’s Chassisworks front subframe. This also gave us a chance to see how our new stainless Hooker 1 7⁄8-inch first-gen LS headers would fit. They weren’t designed for this application, but they fit perfectly and cleared the subframe.
02. We were able to make the marks needed under the Camaro and start removing the top of the factory tunnel, making sure not to go bigger than the tunnel cap we sourced from Chassisworks. The T56 Magnum was supported by the Chassisworks tubular crossmember that’s designed to work with our subframe or with a stock subframe (using adapter plates).
03. Here is what we removed from the factory '68 Camaro tunnel. The new cap will raise the tunnel about 1.5 inches. Not a lot, but enough to clear the new T56 Magnum.
04. This is the transmission tunnel cap from Chassisworks (PN 5922-F10, $101). It came preformed and ready to rock complete with a mating flange on the downward edge. The cap extends from the firewall back to the seat crossmember.
05. We also marked where the shifter would poke through and made the necessary hole.
06. Best of Show Coach Works fabricator Kyle Phillips installed the new tunnel cap on the '68 Camaro and clamped it in place. As you can see, we needed to fabricate a panel to transition to the firewall. For easier panel fitment, Kyle used a marker to scribe a cut line in the top of the tunnel cap.
07. He then used a pair of snips to remove the marked section.
08. With that done, he drilled some holes around the perimeter and used Cleco fasteners to hold the new tunnel cap in place. Cleco fasteners and the required pliers are inexpensive and come in handy when doing all sorts of sheetmetal welding.
09. We then busted out our trusty Millermatic 140 MIG welder, which is a perfect size for sheetmetal work.
10. With the tunnel cap secured by five Clecos and a couple of locking pliers, Kyle started tacking it all together.