Question for ya?

Okay guys, ya know I'm not much of a mechanic and I'm just learning so no 
public humiliation. LOL! All the sudden my little wench is making a 
knocking noise. It's happens only when the wheels are turning and it 
changes speed with the rotation of the tires. Is this my U-Joint going bad? 
If so....how long do I have before the darn thing falls off? LOL!

Tracey in Arkansas
1975 MG Midget "The Wench" (The car NOT the owner...I'm The Twit)