My wiper conversion is complete, and I'm very happy with the result. Following is a summary of what I did. I've posted pictures of some details on my photo site.
I bought my wiper arms from Rock Auto (www.rockauto.com
). They're Motormite brand, part #42710, and the cost is $18.09 each. As supplied, the arms don't have any washer nozzles. These are GM part #22121436 and gmpartsdirect (www.gmpartsdirect.com
) sells them for $9.21 each (nozzle assembly for one arm).
I used a giant tapered reamer and did a lot of Dremeling to get my arms to mount up, but there's a much better way. A 3/4" Unibit (center one in my photo) is apparently a near-perfect taper and makes the hole reaming and tapering process a snap. Be aware that there are probably twenty different styles and sizes of Unibit. I'd recommend that you take one of your wiper arm cones with you to Harbor Freight and buy the Unibit whose taper best matches the cone.
Once you've reamed the hole to the correct size (don't ream too deep!), line a vise with several layers of masking tape and squeeze the cone into the wiper arm to form serrations in the arm. You may want to do some trial fitting first to position the arm properly on the cone. A few washers or a spacer will then take up the extra stud length and let the retaining nuts hold the arms tight.
The wipers are a standard style (Bosch Micro Edge Excel part # 40920) that mounts to a pin on the wiper arm. My '74 Argosy used 20" blades, about 2" longer than original. I think all motorhomes will use this size.
I've tried adjusting my linkage (see John's Cleveland Ignition link), but I think the original setting is probably best. With just one additional "notch" of adjustment, the driver's side wiper goes too far around the corner of the windshield and puts a lot of extra load on the motor.
Total cost was about $100 including shipping the arms and nozzles from two different sources. (You could definitely get by cheaper and do just as nice a job with junkyard parts, but I didn't have time to search for them.) All in all, it's a nice looking upgrade and should be easy to maintain with modern parts sources over the years.
I'm sure there are better ways of doing some parts of this process. I look forward to hearing about them as other folks do this conversion.