Had the same problem on my 87 Raider. Mine was leaking like a sieve, emptying the reservoir in a day. Pulled the steering gear to find there is an outer dust seal and an inner seal that requires the entire gearbox to be torn down. I bit the bullet on a rebuilt unit from AutoZone. price was $256.99 after returning the old steering gear to my local Autozone

Part # 5906
SKU # 10566
Limited-Lifetime Warranty

Notes: Remanufactured

87 Raider
4.3 GM
Edelbrock manifold
4-bbl Holley 390
700R Automatic
B & M Shifter
NP207 transfer case
31 x 10.50's
Superwinch 9500
Brush guard
IPF driving lights
Dual batteries
2000 watt inverter
Yakima roof rack
Hi-Lift jack
Two 20 liter gas can rack