Sure carefully mark the output and input shafts, if possible with something larger like a yoke inserted and a clutch disc and carefully turn the input and count turns against exactly 1 turn of the output
If you are careful you can tell. A way to make it more exact and easier to see is to count the input shaft turns and get TEN turns at the output so now your 2.43 becomes 24.3 and so on. Easy.
It's easy I tell you easy.
