Do you remember how much new fluid you put in when you did the change? As long as you added the recommended amount it's strange that almost a liter of it would disappear with no obvious leaks. Did you measure how much of the old fluid came out?
No I don’t know how much I put in nor how much came out, I changed the rear differential & transmission & engine oil at the same time, I put about 1/3 of a quart of I think it’s called liquid molly in the rear end & the rest in the transmission, then as it turns out the filler tube I found at Walmart would only work on the liquid molly bottle I had to pour the rest of the gear oil into the one bottle to service the transmission oil, I filled it through the dipstick tube for the front differential
As per the factory service manual the front transmission/diff share a fluid capacity of 3.3L or 3.5qt's. The rear diff capacity is 0.8L or 0.8qt's. If I read what you wrote correctly you used 1/3 of a quart in the rear and 2/3 of a quart in the front tranny/diff? If so then you under filled the front and that's why it read low and needed at least another quart.
No I did what my wife calls starting in the middle of a sentence, I brought 4 quarts of GL-5 gear oil one of which was the molly lube from Napa, so like I said I put approximately 1/3 of a quart of the molly gear lube in the rear end & then finished filling the rear differential with GL-5 with a pump, then used a fill tube that I got from Walmart to put the rest of the molly gear lube in the transmission through the dipstick tube & then had to pour the other GL-5 into the molly gear lube bottle & poured it into the transmission through the dipstick tube checking it after pouring some in & it didn’t take as much as I thought it would but it was showing full on the dipstick & so like I said after I don’t know for sure how many miles I checked it & it was to the low mark so I filled it back up & it took almost a quart , but since then after driving for a few days probably about two weeks checking it quite often it hasn’t changed in level