I wont to change my oil and filter. where is the drail plug on my 03 heritage softtail clasic?

It's either in the bottom of the crankcase or you're using a quart and a half between oil changes. Always change the oil when the bike is at operating temprature!

Look at this pic, see if it helps:

many things can cause this ,if you change your seating postion ( lean forward / move backwards does it go away?....

front forks loose at triple tree,
new front / rear tire more aggressive tread than before,
front wheel loose,
worn head bearings,
bent rim,
loose spokes if any,
wrong tire pressures,
loose handle bars
,some new addition to change the handling of the bike , rear seat rest etc,

Look at the bottom of the oil tank from the right side of the bike. You'll see one hose or pipe that goes downwards towards the back of the transmission. The hose will follow the frame and come out way down low on the backside of and slightly under the transmission. There is a plug in the hose or pipe. Take the plug out and the oil tank will drain.

To change the oil, drain the tank, change the oil filter, refill with three quarts of oil in the tank. You also have oil in your primary that should be changed every 5000 miles or so, and the transmission serviced at the same interval as the primary.

To drain the oil on the primary, there is a drain plug under the primary case at the very rear of the case. Remove this to drain the case. Refill the primary through the derby cover. Fill with oil until the level is just to the bottom edge of the clutch spring. 38-42 ounces of oil. Do not overfill or the clutch will drag and make finding neutral with the engine running impossible to find.

To drain the transmission, there is a small plug on the bottom side of the chrome cover on the right side of the transmission. Remove the plug, drain the tranny, and refill through the large plug that takes a hex key in the chrome cover. 20-24 ounces of transmission lube.

Good Luck
Steve

try bikebandit.com

Its at the back of crank box right hand side of bike attached to bottom of frame in a sprung clamp just before the softtail swingarm- black hose with a plug and hose clip