very loud tapping noise from the engine

With the engine running you could listen to the noise using something like a long screwdriver pressed against the block and your ear to the top of it. Generally a small end will be noisy all the time whereas a big end will make most of its racket under load. Why do you want to access the bottom end? If it is the/a small end then the piston and rod will need to come out through the top. You could get all the bolts of the sump off but whether it will angle enough to clear the oil pickup is another thing.

its in a 2003 soft top think we talking dealer parts so i think an other engine in order. is there a difference in variant between hard and soft top? also will my ECU run a new engine? thanks all

If your sourcing a new engine why not fit a 1.6?

Your soft top will have a different cam pick up ring on the back of the cam, a different sump and different inner crank pulley to trigger the crank sensor. The early hard tops don't have these but all parts are interchangeable. So if you got an early g13b you would need to swap sump, cam or just the ring, inner crank pulley and drill an 18mm hole for the crank sensor. Its all easy stuff. I think there is a g13b hard top engine on eBay

i was tempted at a 1.6 but i need to get the jeep going again as fast as possible where on the engine can i find identifying marks ? thanks all

Look under the car up at the crank pulley just in the sump should be the crank sensor