Ok so a few people have been chasing info on 4.0ls lately, so over some period of Time I will start posting what I know about 4.0ls as I have played with them for years , this first post is taken directly from a post i made in ph351's thread earlier today,<br /> Ef and early El are the same, late El.used a Au style head and crank, without the longer con rods (if you see an El engine with the prefix wr2axxx cat into it it's an Au style head with 1.8:1 ratio rockers compared to the earlier 2:1 ratio) and the camshafts don't interchange between the two ratios, Ef or El cam be set up for a distributor or coil packs (ea- can also be setup for coil packs but it requires a Ef/El timing cover, also to change from v belts to sepentine belt requires Ef/El timing cover and balancer *note v belts cannot be used with a Ef/El timing cover with stock brackets) pre Au: ea's have the strongest rods, ef's have the best crank (12 counterweights compared to 8 on all other e series) Ef/El blocks are better as they have oil restrictors in the top of the block to prevent to much oil in the head at high rpm (makes for more stable valve train above 4000rpm) ea cam is the biggest for made for a 4.0l (except xg xr6 but good luck finding one) and cannot be used on a Au without custom rockers, xr6 head use standard intake valves with a larger exhaust valve, they were also a different casting from a standard head with similar intake Ports but a much better exhaust port (the best xr6 heads to get have the casting no 93dt and 94Dt, the best of the non xr6 heads have the casting 94da). Au egas engines use better crank and rods than a standard petrol engine (also slightly higher comp, and an Ef xr6 head on an Au egas short nets 10:1 comp) Au engines can take a BA turbo crank and rods without machine work, Au rods are longer than e series with a hypertectic pistons (same advantage as using 3.3 rods in a 4.1 or 302 rods in a 351) a really nice Combo (what some of you will remember I had in my xh) is Au egas short motor, Ef xr6 head, ea cam, El intake with a set of extractors and a tune made 178 rwkw for less than $600<br /><br />