where the cracks used to occur. Also new for the 2000 model year, was the distributorless, coil on plug ignition system. Option code: ERH. Output: 1987-90: at 4500 rpm and at 2500 rpm 1991-95: at 4750 rpm and at 4000 rpm 1996-01: at 4600 rpm and at 3000 rpm 2001-06: at 4600 rpm and at 3200 rpm The 4.0 engine was discontinued at the end of the 2006 model year, replaced in the redesigned 2007 JK Jeep Wrangler by Chrysler's 3.8 L OHV V6, which originated in the company's minivans. This engine was used in the following vehicles: 1987–2001 Jeep Cherokee 1993–2004 Jeep Grand Cherokee 1987–1990 Jeep Wagoneer 1987–1992 Jeep Comanche 1991–2006 Jeep Wrangler Connecting rod lengths 1964–1970: - - - 1971–2006: - - - - The displacement differs between 1990-1995 and 1996–2006 4.0L engines by around . Both had a bore of , but the stroke decreased slightly from on the earlier engine to on 1996 and later engines. The small stroke change of was accomplished by moving the piston pin and changing the crankshaft stroke; the rod length did not change. The deck height of the AMC six cylinder block was increased by (half the rod length difference) in 1971 to allow for the longer stroke required for the 258. Only two deck heights. Tall deck is . Short should be . Tall is from a 74-76 AMC factory service manuals, prior to 1974 deck height was not printed. Deck height changed slightly over the years 1977–1982 service manuals state , the 1993 Jeep factory manual states . Deck heights may have changed to accommodate slightly different compression ratios over the years. The 1971 and older blocks use a "small" bell housing bolt pattern that is exclusive to AMC and small Nash sixes. In 1972 the bell housing bolt pattern was changed to match the AMC V8's - its final use was in 2006 when the 4.0 was phased out. Four bolts on the cylinder block are matched to the transmission bellhousing where an adapter plate serves both as a dust cover - two additional bolt holes on the transmission bellhousing used on the AMC V8 are used to secure the dust cover. The 1971 model year 258 uses the "small" pattern, the only version of the 258 to do so. See also AMC straight-4 engine AMC V8 engine AMC Engines AMC and Jeep transmissions List of Chrysler