Plontzies88TransAm

I'm rebuilding my tilt steering column on my 89 Pontiac Bonneville SSE after a theft. It has the same Saginaw column as my 88 TA. I need to replace the lower column housing that was broken and in order to do this I must remove the upper driveshaft from the lower driveshaft. the two driveshafts are joined at a knuckle that I cannot figure out how to disassemble. Any help would be greatly appreciated. Thanks