Does anyone know what the Kent-Moore "J" number is for the HO52 differential holding fixture? I found a J-6177, but didn't measure my HO52 before ordering it. The J-6177 is obviously for much larger differentials. If I had the means to make an attachment, I could simply build something that added on to the J-6177, but I do not have that option, and have to return the item. So, I am asking for the "J" number if someone knows it. Thanks.