As far as I understand, the construction is the same, but some details (like friction plates) are different. So, you are right, A343 is beefier. I checked this application guide:

http://www.automaticchoice.com/Catalogue/aw_340.pdf

Oleg
Axiom 4WD 2004: OME shocks, 32" BFG Mudders, RockSliderz, OME929+2" spacers, Stinkyfab bent RE rear links, front ARB locker, rear No-Slip locker, DOR front axle lowering kit, custom middle section skid plate, IronMan torsion bars.
Deceased Rodeo'02 4WD.