Assuming that your 3510 is built the same as my 4110, the driveshaft from the trans to the front diff isn't too difficult to remove. To begin with you loosen the clamp that is about midway down the tube, this lets the 2 sections of tube slide together thus shortening it. The rear section slides out of the front of the trans and has an "O" ring for sealing. There should be a little tab of metal on the tube back just in front of the trans, this is for tapping on gently with a hammer to get the tube out and/or back into the trans. The front tube has a small ear on it and a small bolt holds it to the front differential, remove this and you can move the collapsed tubes back & forth along the actual driveshaft inside. At each end of the driveshaft you'll see the splined collar with a snap ring on the shaft on one side of the collar. Using snap ring pliers open this snap ring and slide it down the driveshaft a little ways and this will allow the collar to slide as well, disengaging it from the corresponding shaft it attaches to. It is the same at both ends - once you have both collars slid back the whole driveshaft and tube assy will fall right down in your hands or on your head if you're not careful !! There is no fluid/oil inside this tube assy, just the driveshaft. If there is fluid you have a leak - 90w gear oil from the front diff or hydraulic fluid from the trans. Good luck on your project !!