weight of 383 engine??

I need to ship Fastenal/ Does Fastenal actually weigh the darn thing or will they just assume this weight close enough?? I really have more to do than make a couple of trips to a scale for exact weight.
I’ve shipped using Fastenal several times. The price doesn’t change much with weight. It’s more of the actual space (dimensions) that you need. So I will guess the weight and add some to be sure.
I’ve seen them weigh it at times, it depends on the staff.
There is a compliance sheet they sign and it lists the dimensions and weight.
I had a shipment that I picked up and the sheet stated that the dimensions were larger than originally stated but the store didn’t charge me more for it.