Most vehicles that use similar design axles that come with OE synthetic gear lube recommend 90-120k interval for light/normal use and 60k for more severe use (towing etc).
FWIW, as far as the t-case goes, Toyota suggests a 30k interval when towing compared with the axles 15k towing interval.
I do tow a little and I changed all three to synthetic at 5k to get the shavings out. I will change all three (with synthetic) at 45k, 90k etc or 3-4years, whichever happens first. I am probably doing it too frequently but that's how I roll
If you said you want to run 60k on all three you'd still be doing way better than those who maintain to the non-towing standard.
Most vehicles that use similar design axles that come with OE synthetic gear lube recommend 90-120k interval for light/normal use and 60k for more severe use (towing etc)...
I changed it at the 64000 Km (40K miles; as recommended on the stealers schedule) in May '06. I won't rush to do it this spring. I'll go longer with the synthetic, beyond the 128000 Km, probably 160000 to 164000 sometime this fall with very moderate intermittent towing.