I know it's not the news you want to hear, but the only safe recommendation I can make for you would be to find a place you can park your trailer, pull the hubs and get the seals and bearing numbers so we can get you the right parts. I know it's a pain and it leaves you with a trailer stuck on jackstands till you get the right parts but it's the only option.
Hexagonal caps that are threaded are typically used on oil bath hubs.
I would recommend you at least inspect all the components... view full answer...
You are correct that the SportRack # SR1098 does not fit on vehicles with naked roofs, like your 1991 Volvo 740 Wagon. For that reason you'll need to use something like the Inno Roof Rack that uses parts # INB127 and # INSD. This Inno rack gives you a great quality rack at a value price and will attach via the rain gutters on your Volvo.
I've attached a review video of this rack for you to have a look at, as well. view full answer...
That certainly does appear to be an oil bath hub. The seal number is associated with 1956 to 1959 Studebakers as far as I could find. It looks like the dimensions of the seal are 1.875 inches inner diameter and 3 inches outer diameter. We have one seal that has the dimensions, # 29031, but it is a grease seal, not an oil seal.
The bearing # 1779 is associated with race # 1729. They fit hub 22834 which from what I could find is not an oil bath hub. The inner bearing that is associated with... view full answer...
I spoke with my contact at Thule and she informed me that yes this Replacement Square-Bar Clamp-On # 853-2156 would work as a replacement adapter for your ski carrier to mount to Thule square bars. view full answer...
Yes, I checked with Thule and the Thule Passage Trunk Mount 2 Bike Carrier, item # TH910XT, will work on your 1987 Volvo 740 Sedan.
I was also informed that the TH911XT three bike rack will also fit your vehicle. view full answer...
The Yakima replacement parts kit you referenced, their Replacement Hitch Bolt, Nut & Clip for BigHorn 4 Bike Carrier # Y8780022, includes parts required to secure any of a number of their different hitch-mount bike carriers to the 2-inch hitch receiver on a vehicle.
The Yakima racks this kit works with are listed on the product page, and they include several current and even discontinued items. view full answer...