I couldnt find any gl5 dino gear oil at the local auto store but I did find "Lucas High pwerformance havey duty 80/90 plus gear oil" to top off my tranny which seems to be about 1/2 qt low. It says this oil replaces 80W90 and gl5 even gl6 rated gear oils. "Excellent for use in limited slip differentials with no special additive needed....excellent for use in race cars, trucks, rv, hypoid gears"
i know 1/2 qt wont matter much but I wionder if anyone has experience running straight Lucas gear oil, which exceeds gl5 classification. Since it is a little thicker than 75W90, I figure the synchros might like that.