"T/A 6.6" At the end of 1976, Pontiac was no longer able to continue production of the 455 (7.5 L) V8 motor due to the tightening emissions requirements. As Pontiac still wanted to offer a performance motor to compete in the performance market, they looked back to the 400 Pontiac and how it could be improved to offer greater performance while meeting CAFE standards. In 1977 the T/A 6.6, (RPO code W72) was created to fulfil the performance engine gap in the Pontiac line-up. The W72 offered many improvements over the standard L78 400 Pontiac. One of the key upgrades were the 6x4 heads. The standard head seen on an L78 400 Pontiac was the low compression 6x8 head, while the 6x4 head seen on the W72 had hardened valve seats for a higher RPM operating range, improved air flow, and higher compression. These heads can be distinguished from 6x8 heads through a small stamped "4" on the top of the front boss. The head design was incorporated from the earlier 1970's 350 Pontiac heads, and could satisfy emissions in all states except for high-altitude emissions states and California. The W72 also featured a camshaft with a higher duration, finer tuned 800cfm Rochester Quadrajet, insulated fuel line, larger 60PSI oil pump, chrome valve covers, a larger harmonic balancer, and the "T/A 6.6" Shaker decal. All of these improvements provided the W72 with a power rating of at 3600 rpm and of torque at 2400 rpm, while the standard L78 400 only produced at 3600 rpm and of torque at 1600 rpm. The W72 engine was standard in all 1977 Pontiac Can Ams (bar the 1977 Can Ams sold in California/High Altitude states which received the L80 Oldsmobile 403) and was optional in all 1977-79 Pontiac Firebird Formula and Trans Am models. The W72 package was a standalone option, and although was discounted when ordered in conjunction with the Y82/Y84/Y88 Special Appearance package, did not come included with Special Edition Trans Ams, it remained an extra cost option. With some WS6 "Trans Am Special Performance Package" bundles in 1978, the W72 engine was incorporated with the WS6 option group and not listed on the dealer order invoice. However, it can easily be determined by examining the cost price of the option, where the package excluding the W72 engine cost $251, and with the engine, cost extra at $324. All 1977-1978 Trans