Does anyone know the inner diameter of part #976734?

I have been getting nickel and dime REAMED by the dealership on these parts.
Initially I ordered what I knew I needed from FCP, but since then I have had to replace some things unexpectedly (like the "Vacuum Tower" / Niple above the Throttle Body) because I broke something brittle in the process of changing. My local dealers are charging (in some cases), 4 times that of FCP. Like on the front cam oil seals - FCP = $5 each, Local Dealer = $20 each.

Anyway, Naturally I got the elbows and plastic lines as Volvo OEM parts. For all other vacuum lines, I got general auto store tubing for washer/vacuum lines. Just as I thought I was finished, I found one more line - !@#$#$%^&*())_

This line runs from the inlet manifold (off nipple #3 on the Vadis diagram) back to the turbo.

I pulled the line and took it back to Pep Boys to size it up. I found that the diameter on the ends was wider than the middle. Also, the thickness of the rubber on the original was about 50% wider than that of what I could find at the auto parts store.

I figured the ends just got stretched and hardened with heat and time, so I bought a hose that equaled the diameter of the middle which was 7/64". But when I got it home it was too small. Now I wondered if it were a special hose, mfg'd like some of the elbows to varying size on the ends.... But when I called the dealership they gave me the part number listed at the top here and said it was sold by the meter, which means the size would be the same through and through. I am on my way back to Pep Boys to get the next size up (5/32" I think).

BTW, last trip to Pep Boys got me a speeding ticket. Cop said car in front of me was going faster, but because of the "flashy" motorcycle I was riding, it caught his attention. SO there goes $100 I was trying to save ~!@#$^&()+

Can anyone tell me if I can get away with using a general auto store vacuum hose, or if there is a good reason I should go with Volvo OEM lines @ $20/meter
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1995 850T Wagon 120k