Shotguns with this trade name were made by Crescent FIre Arms, Crescent-Davis Arms, Iver Johnson, and J. Stevens. Share the model number and I may be able to tell you which one made yours.
Excel shotguns were made by a couple of different manufactures, notably Crescent Firearms and Iver Johnson, for sale by Montgomery Wards through their catalog before World War 2.
You will have to carefully note exactly how the gun is marked, first.
Where will be marked on the barrel/receiver.
Should be marked on the barrel
It will be marked where it was made.
Have it examined by a gunsmith
I have one marked "model 155" has no serial # and was purchased in 1964
Sure can't tell over the internet without a lot more information. The model name or number is PROBABLY marked on the barrel or receiver. If it isn't there I might be able to help if you describe the gun and tell everything that is marked. Or you can look for it in The Standard Catalog of Firearms.
Start by telling us everything that IS marked on the gun. Those numbers may be a Montgomery Ward model number which will probably cross-reference to a manufacturer's model.
Shotguns are described by gauge, not caliber. It should be marked on the barrels as to which is the correct ammuntion and gauge. Shotguns are described by gauge, not caliber. It should be marked on the barrels as to which is the correct ammuntion and gauge.
Use a thread gauge to find the number of threads on a bolt. A thread gauge is several comb-like plates, each plate is marked with the number of threads the gauge fits. Search the internet using thread gauge for examples of what thread gauges look like.
Remington's website has a history section that you can look at.