all 1985–1991 Corvettes. It was rated at for 1985–1986, for 1987-1989 ( with 3.08:1 rear axle ratio (1988-1989 only)), and in 1990-1991 ( with 3.08:1 rear axle). Aluminum cylinder heads (Corvette only) were released part way through the 1986 model run, modified for 1987 with D-ports, and continued through the end of L98 Corvette production in 1991 (still used on ZZx 350 crate engines until 2015 when the ZZ6 received the fast burn heads). The L98 V8 was optional on Jan. '87–'92 Chevrolet Camaro & Pontiac Firebird models (rated at - and -) The 1987 versions had and more and a change to hydraulic roller camshaft. Compression was up again in 1990 to 9.5:1 Camaro/Firebird and 10:1 Corvettes, but rated output stayed the same. Vehicles using the L98: 1985-1991 Chevrolet Corvette 1987-1992 Chevrolet Camaro (optional) 1987-1992 Pontiac Firebird (optional) L05 The L05 was introduced in 1987 for use in Chevrolet/GMC trucks in the GMT400 (introduced in April 1987 as 1988 models) and the R/V series trucks such as the K5 Blazer, Suburban, and rounded-era pickups formerly classed as the C/K until 1991 which includes chassis cabs and 4-door crew cabs. The L05 was also used in the G van models and the P30 step vans. Additionally, the L05 was used in 9C1-optioned police package Caprices, and in the following vehicles: 1992/1993 Buick Roadmaster sedan and station wagon 1990–1992 Cadillac Brougham (optional engine) 1993 Cadillac Fleetwood 1989-1993 Chevrolet Caprice 9C1 police package (roller cam); 1A2-optioned special service station wagon 1992/1993 Chevrolet Caprice wagon (optional engine) 1993 Chevrolet Caprice LTZ 1992 Oldsmobile Custom Cruiser wagon (optional engine) 1991-1994 GMC W4500 Tiltmaster / Isuzu NPR gas 1995-1996 AM General Hummer H1 L05s were used primarily with casting number 14102193 (64cc combustion chambers) cylinder heads with swirled intake ports - the intake ports were designed for fuel economy (the design was also shared with the 103 heads used on the 4.3L with TBI). The swirl ports (known to GM as a vortex chamber) along with the irregular shape of the combustion chambers limit the airflow and horsepower output where they did not provide a fast burn, later phased in with the 1996 Vortec heads. A majority of the L05s used with the trucks and vans had conventional flat tappet camshafts, while the Caprice 9C1 (1989–93) had a roller cam. L05 usage was replaced by the LT1 after 1993 in GM B-Bodies and D-Bodies until