T in '90 truck
I took a trip up to manufacturer in Pasco, Wash. to have one installed a couple of years ago. It was easy. The narrow end that will fit into the '94 and up turbos is too large to fit in the early turbos, so just turn it around so the collar is firmly set against the turbo inlet, place the clamp around both the collar and the turbo inlet and tighten very firmly. This device does work well, especially when towing. Faster acceleration resonse, improved milage. I don't see any downside. I don't think the the TAG II or III will work on the first gen. trucks.
My truck: '90 2WD. Aftermarket intercooler, 1992 radiator, BD exhaust brake, 60lb valve springs, TAG, High Tech exhaust manifold and 14cm wategated housing for WHIC and HX35W Holset turbos, original injectors retipped by Goff Diesel Injection with Bosch 7762 industrial application nozzels and new ATS 48RE transmission with triple lock torque converter and uprated valve body.