2.9l Oil Leak Parked Uphill

[TSS246]

Finally got my 1986 ranger done enough to drive around town today, I just swapped in a M5OD-R1 and did the rear main seal while the old trans was out a year ago. Driving around town I didn't notice a leak but I parked on a steep 6ft pile of dirt to get some photos and after sitting for a few minutes I noticed a decent amount of oil on the dirt under the truck. It was leaking out of the gap between the engine and the bellhousing, Is this a rear main seal leak or could it be something else? I'm just confused because it only leaked when parked uphill. Thanks in advance to anyone that responds!
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[rusty ol ranger]

Finally got my 1986 ranger done enough to drive around town today, I just swapped in a M5OD-R1 and did the rear main seal while the old trans was out a year ago. Driving around town I didn't notice a leak but I parked on a steep 6ft pile of dirt to get some photos and after sitting for a few minutes I noticed a decent amount of oil on the dirt under the truck. It was leaking out of the gap between the engine and the bellhousing, Is this a rear main seal leak or could it be something else? I'm just confused because it only leaked when parked uphill. Thanks in advance to anyone that responds!
. View attachment 107359

Rear main or pan gasket would be my guess