Brake Caliper Bolt Part #???

[PropXprt]

The guys at the dealership were worthless in finding what bolt goes into the hole I have highlighted on the picture below. If any of you can figure out what part number I need for this "guide pin" or whatever this thing is called, it would help me out alot.
Thanks

 

[steve]

Can't tell since the picture is washed out it that's a front or rear caliper, my guess is that's it's a rear. Here's all the bolt part numbers for a '91 AWD

MB534413 Rear Lock Pin M8
MB238735 Rear Guide Pin M8
MB618227 Front Guide Pin M15
MB618228 Front Lock Pin M15
MB618215 Front Lock Pin Bushing

Steve

 

[PropXprt]

Thanks, finally figured out what problem was... guy at dealer had front caliper up instead of rear.