I just did my diff oil. It was 30min and $20 taking my time. Did it on the garage floor. Super easy to do. Easier than than either diff in my lifted 79 K5. Air filters are about the same price and take a few minutes...

I'll be tackling the manual trans oil next. From what I've read it's a tight fit, so going to use a friend's lift. Is yours auto or manual? Most things on this car seem to be rather easy to fix/maintain, but then I've never taken a vehicle to anyone for repairs or maintenance.