Sounds like you probably have it, you will find the starter too damn heavy! If you get it out and want something more reasonable Tom Telesco
can supply a mini starter which will be lighter and perform better than your original could ever hope to!
Remove top bolt first as it is difficult to get at. GM had a special "curved" wrench for this purpose.
I hunted for several years to find one and finally did at a garage sale. You can do it with an extension
and a crowfoot