As a former truck driver, mechanic, dispatcher, and fleet manager whose best friends are truck drivers and mechanics, I feel I can say this with utmost certainty.
You're supposed to keep your truck in much better condition than you're describing. Mechanical systems such as drivetrain, brakes, and fifth wheel should be in top working order. Electrical systems should be 100% functional. There should be no fuel leaks, air leaks, hydraulic leaks, refrigerant leaks, or lubricant leaks. These rules exist so that the roadways are safe for everyone, including you, me, other automobiles, and other truckers. You're supposed to inspect your truck every morning and confirm it's safely operational. Every trailer you hook to should be inspected to the same standard.
If DOT knew you were driving around with a slippery clutch and a nearly blown rear end, they'd have parked you.
Find a reliable mechanic who can service your truck affordably. Dealerships and service shops like the T/A are generally very expensive. Keep in mind that you're driving a commercial vehicle that is intended for heavy hauling of valuable goods. While $8800 is no drop in the bucket, it's not out of line for repairs like this.
One friend hit a deer in his Freightliner Classic two years ago; his new hood alone was $20,000. Another hit a large tree limb with his company's trailer and the repair charge was over $5,000.