73 vs. 76 cases

i am putting 1015 cylinder on my 900 cases. i have two cases to choose from though, a 73 and a 76. the 76 seems to have thicker metal on the lower case half underneith where the crank goes. i was thinking using the 73 for lighter weight but then i got to thinking is there a reason the newer one has thicker metal and is anything else different on the engine i should know about? i need to use the 73 gears no matter what because the second gear on the 76 is ruined. thanks, ryan.

hang on to those 73 cases theyre worth some money.those old 900 cases are all pretty tough if you put the extra main cap brace on them and a good set of main studs,but even that is overkill in most situations though.