Redline MT90 is the best for the AisinWarner AX5 and AX15. I'd say use Penzoil Synchromesh as a second choice, I don't think it's synthetic like the Redline.
As for you jeepers with the CJ's and the '87-'89 that have the Peugeot, these two gear oils may not provide you any benefits and may not justify the extra expense. I only know of the AX5 and AX15 having the problem with the GL5 being corrosive to the soft brass synchonizers. I'd check into using a quality off-the-shelf synthetic 90W or whichever your owner's manual or FSM recommends.