Nissan lower unit stuck

[bowhunterjac]

I need to replace the impeller on my 18HP Nissan NS18E2. I'm having a real problem getting the lower unit off. I don't know if or when this LU was dropped last. I've disconnected the shift linkage and taken off the 4 nuts and washers. I'm hoping I'm not missing another hidden nut or bolt somewhere. I did find a small bolt in the pocket just in front of where the shift linkage goes into the lower. It was a real bugger, but I got it out too. No luck with the LU. With a good bit of pounding I got the rear part of the LU down about 1/16 of an inch. I've sprayed it down around the bolts with CB Blaster and hit the area of the bolts with a little heat. I hate to pound enough to break something, or heat enough to harm something. Does anybody know if there are any hidden bolts? Or I've read that some units require the shifter to be in forward for the LU to drop??? Iv'e also read of people using wooden wedges. Do they use wooden shims? Anything else that I can wedge in there like a screw driver etc... without prying it.
Or does anybody have any other suggestions? I've done a few of these before with no issues, 1/2 hr job, back on the water.