I'm not sure I can be of any help, but I'll sure be watching since my L35 is only a couple of years newer than yours, but has almost exactly the same hours.
As you may be aware, there is a regulator valve in that pump circuit that gives priority to the transmission as shown below:
View attachment 57193
When I got mine about two years ago, it had a definite 'chirp' when shifted, but I never noticed any steering issue. I replaced all the suction line hoses and fixed a crushed steel line between the transmission and filter.
Those suction hoses are a common problem, and you won't see a leak because they're all above the fluid level, so there's no positive pressure on them even when the tractor's not running.