Yes the spline is the same.
I don't know exactly how the steering wheel fits, By that I mean what stops it, what does it bottom out on when installed. I don't know where or what the "shim" will do. Are you worried how it will look or how it will rotate with out hitting the tube? A pic of the top of your tube with wheel ready to install, pic half installed and pic installed, all taken from bottom/side angle. I can then answer the questions if no one else responds.
Does the 1.75 tube have to go inside the bottom skirt/recess of the wheel to look right.....or butt up with a clearance gap. Again, what built-in stop is there to prevent the wheel from rubbing on top of tube on a 38/41 combo?
You speak of a shim/spacer "inside" or "down inside" something?, so you must mean a washer style shim with an OD that fits into the 41 wheel recess and an ID that fits over the 38 spline. You must be trying to keep the wheel from rubbing on tube top? That seems to create a very thin walled "shim"????? Like an Oring? or a slice of a piece of tubing?
Sorry, but only those with a 38 or near 38 will know what is all looks like and what you are talking about. I'm a little handicapped so need detailed explanations.
