I have my doubts but if you had them side by side you could see if they are the same.
i have measured and counted the splines and gear on starter even though the starter is an inch shorter in length and the cable pole is in the wrong position but can be moved around by undoing the three 7mm clamping bolts it all seems the same as the 1500 starter,
i did a experiment around a year ago with a gl1800 valkerie starter motor they are about 1 inch shorter than the 1800A starters but i changed the front starting gearbox from one to the valks and a year later it is still working fine on my wing.. think i paid around $70 for it and the 1800A starters go for a lot more than that and the valks don,t work as hard as no reverse on them