To keep things simple we could have bolted the Ram Jet up to our original TH350 transmission - and if it were in good shape we might have. But for the kind of use this truck was going to see, we gave TCI Auto a call and spec'd out a Truckmaster TH350. TCI recommended we go with its optional 2.75 ratio First gear (stock is 2.52:1) and a heavy-duty case (PN 311210) for $1,784. We put a lot of faith in TCI's products because every transmission it builds is for an enthusiast application. Everything in the transmission, from the friction material used to the way the shift feel is calibrated is done for a 4x4 that is gonna get used hard every time we get behind the wheel. Since we had our Ram Jet 350 on the hoist, we bolted the TCI TH350 to it with a flexplate for an '89 Blazer with a 350 ($43 at Autozone) and a 12-inch TCI torque converter ($269).
The strongest engine you could get in a '75 K10 was the optional 400ci small-block rated at 175 hp and 290 lb-ft of torque. That's nothing to brag about and wouldn't have been enough for 39-inch tires and a truck that's gonna weigh almost 6,000 pounds. Last month we told you that our buildup was going to require at least 350 hp, fuel injection, and would have to stay small-block based for weight and cost concerns. After crunching all the numbers, we just couldn't beat the value of the Ram Jet 350 ($4,900) from GM Performance Products. For the price of some aftermarket fuel-injection systems, you get the complete engine-oil pan to air filter-with the multiport fuel injection, computer, wiring harness, 350 hp/400 lb-ft of torque, and 2-year/24,000-mile GM warranty. The Ram Jet 350 can be installed in any vehicle that came with a small-block Chevy, but to make sure ours stays in place when Editor Rick Pw hammers it, we fastened it in with Off Road Design's competition-style motor mounts ($165).
While Hughbanks was manning the engine hoist, we slid under the truck to fit the original '75 crossmember back in place with new Daystar polyure-thane transmission mounts ($82). We didn't have to fabricate anything or use any adapters because it all went together like the stock parts did. The lowest point on our truck will still be the transmission crossmember, so we'll plan to build a skidplate to protect it and the TCI finned-aluminum transmission pan ($140) that holds two extra quarts of ATF.
Next month we'll pick up where we left off with the engine wiring, cooling, and fuel plumbing. We're probably gonna have to test fit a few different kind of headers to find some that will clear our driver-side driveshaft, yet still fit in the '75 framerails. And we're also tracking down a cheap accessory drive system that will let us run a serpentine belt--and maybe even get the A/C working again. If you've got one let us know.