Between Omaha and Des Moines, 7 miles South of I80 | Two things: #1: If you had the actual CAT 5/8" 12 pt. swivel starter removal tool, then you would just add enough extensions to it, to get "passed" the front of the starter and then USE a very long breaker bar = much stronger than any impact, once "extensions" are being used = I've removed plenty "upper starter bolts" this way. #2 Get the BEST quality of 5/8" 12 pt combination wrench, and put the "box end" on the head of the starter bolt. Now, fist try to "double up" with a second long comb. wrench , for leverage (just to break loose) BUT if the "Angles" don't work out, for that idea(two wrenches) then use a BIG 4-6 foot prybar, against framerail, and pry against your BEST 5/8" combination wrench that is on starter bolt. I've even used a "stubby combination wrench" with a huge prybar to do this. Note: Certain brands of 12 pt box ends, are "cut" differently, in relationship of a 12 pt notch to its handle = comparing different brands may assist you to "position" the wrench on the starter bolt. Example: MAC is different than Snap-On |