First, welcome to our community forum easthamaw
And second thank you for purchasing our kit! I love mine to death!
...the front two are inaccessible even with a flex head wrench (had to buy the metric set). Sheet metal surround is directly over the bolts and the shifter body blocks wrench access from the rear...
Easiest solution would be to put a floor jack under your crossmember, detatch it from your frame, and then lower the transmission down about an inch or so. It doesn't need to be lowered much. Wouldn't need to disconnect anything else. Then jack it back up when done.
It's possible someone changed bolts on ya. They are supposed to be a 8x1.25mm bolt with a 12mm head. Pictures help if more assistance is needed. Our instructions really make the job easier than it seems. After you've finished one you'll suddenly feel like a short throw installer pro and will probably be looking around your neighborhood to see who you can install one for