Which Carrier Bearing?!

[Disco]

Hey all! My driveshaft carrier bearing is going bad - the rubber isolator is crumbling and has delaminated from the bracket. I want to order parts, and of course GM has two options, a 1.38" (35mm) and a 1.57" (40mm). My bearing has the horseshoe style bracket.
I'm not doing the job myself, as I don't have a press, but I want to bring a bearing with me to avoid parts markup and delays. But I don't know which bearing to order. Does anyone know if there's a way to tell without removing the driveshaft? Thanks!

Specs:
SWB Big 10
350 V8
SM465
12-bolt
6050 lbs GVWR

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[83K31003]

Any particular year model ?

Looked up a ‘77 model ( just a guess ) on Rockauto C-10 LWB and most of the 1310/1350 jointed shafts use the smaller size bearing.
Don’t trust it though - a direct measurement is the only certain method.